Remove Win 10 from Win 11/10 dual boot?

CalypsoArt · Apr 27, 2024

My laptop (MSI GS75 Stealth 9sf) came with Win 10. Eventually I upgraded to Windows 11 on a second hard drive. I often do that so I can take my time setting up the new system while having access to the working old system. Anyway, It's been a few years and I haven't used the Win10 install in forever. I'd like to remove it/format the drive. If I remember correctly from when I did this way back, (Win 7 to 10) it was problematic deleting the OS install that was used to create the dual boot. I'm not sure if that is still the case? Anyway, can I remove the Win 10 OS and not affect the working 11. And if so, what is the best method?

Brink · Apr 27, 2024

Hello,

Since you have each OS on a separate drive, removing W10 will be much easier using the method in the tutorial below.

How to Remove and Uninstall Windows 7, 8, or 10 from Dual Boot PC

How to Remove and Uninstall Windows 7, Windows 8, or Windows 10 from Dual Boot PC

www.tenforums.com

Megahertz · Apr 27, 2024

If you have installed Win 11 with the Win 10 drive in place, win 11 is using the Win10 boot manager so you can't remove Win 10 without creating a boot manager for Win 11 on the Win 11 drive.
Please post a whole window Disk Manager image of ALL your drives. Don't forget to expand the columns so we can read them. How to Post a Screenshot of Disk Management
If you have a MiniTool or AOMEI Partition use it instead or Windows disk manager.

aubergine · Apr 28, 2024

Remove/format your Windows 10 drive. And after this create a new EFI system partition.

- Boot the computer using the Windows 11 USB flash drive.
- On the first screen press SHIFT+F10 to bring up the command prompt.

diskpart
list disk
select disk # (replace # with the number of your Windows 11 disk)
list partition
select partition # (replace # with the number of the Windows 11 partition)
shrink desired=300
create partition efi size=300
format quick fs=fat32
assign letter=z
list partition
list volume (note the volume letter where the Windows 11 is installed)
exit

bcdboot x:\windows /s z: /f uefi

- replace "x" with the volume letter of the Windows 11 partition
- z: is your EFI system partition you assigned above

BCDBOOT copies the boot files from the Windows partition to the EFI system partition and creates the Boot Configuration Data (BCD) store in the same partition.

UEFI(Unified Extensible Firmware Interface) and How is it Different From BIOS - GeeksforGeeks

A Computer Science portal for geeks. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions.

www.geeksforgeeks.org

Difference between the Booting Process with BIOS and the Booting Process with UEFI

Booting Process With BIOS
- When BIOS begins its execution, it first goes for the Power-On Self Test (POST), which ensures that the hardware devices are functioning correctly. After that, it checks for the Master Boot Record in the first sector of the selected boot device. From the MBR, the location of the Boot-Loader is retrieved, which, after being loaded by BIOS into the computer’s RAM, loads the operating system into the main memory.

Booting Process With UEFI
- Unlike BIOS, UEFI doesn’t look for the MBR in the first sector of the Boot Device. It maintains a list of valid boot volumes called EFI System Partitions. During the POST procedure, the UEFI firmware scans all of the bootable storage devices that are connected to the system for a valid GUID Partition Table (GPT), which is an improvement over MBR. Unlike the MBR, GPT doesn’t contain a Bootloader. The firmware itself scans the GPT to find an EFI System Partition to boot from and directly loads the OS from the right partition.

CalypsoArt · Apr 29, 2024

Megahertz said:
If you have installed Win 11 with the Win 10 drive in place, win 11 is using the Win10 boot manager so you can't remove Win 10 without creating a boot manager for Win 11 on the Win 11 drive.
Please post a whole window Disk Manager image of ALL your drives. Don't forget to expand the columns so we can read them. How to Post a Screenshot of Disk Management
If you have a MiniTool or AOMEI Partition use it instead or Windows disk manager.

Before I go forward with this. The windows disk manager results.

Megahertz · Apr 29, 2024

CalypsoArt said:
Before I go forward with this. The windows disk manager results.

Please confirm that drive 1 has Win 10 drive 0 has Win 11.

As you can see only drive 1 has the EFI boot manager partition and a recovery partition.
It also has a factory recover partition (20G) that is useless.

Are both drives SSDs?

Open a CMD window as administrator and type:
diskpart
select disk 1
list part
exit
reagentc /info

Please post the results here

I'm thing on the solutions.
Do you have a drive image software like Macrium Reflect or Aomei Backuper?

CalypsoArt · Apr 29, 2024

Megahertz said:
Please confirm that drive 1 has Win 10 drive 0 has Win 11.

As you can see only drive 1 has the EFI boot manager partition and a recovery partition.
It also has a factory recover partition (20G) that is useless.

Are both drives SSDs?

Open a CMD window as administrator and type:
diskpart
select disk 1
list part
exit
reagentc /info

Please post the results here

I'm thing on the solutions.
Do you have a drive image software like Macrium Reflect or Aomei Backuper?

Both drives are SSD. One is a Samgsung 980 SSD 1TB, the other a WDC PC SN720 SDAPNTW-1T00.

I don't have drive image software, though I thought there was a free version I used before on my Desktop? I think it came with an SSD I purchased. I used it to partition at some point, but probably removed it.

Megahertz · Apr 29, 2024

Please confirm that drive 1 has Win 10 drive 0 has Win 11.
Did drive 1 came from another computer (Dell, HP etc)? If positive, was the original OS Win 7 or Win 8?
You didn't run reagentc /info

There are two options?
Option 1- Create on drive 0 a EFI and a recovery partition and delete EFI, Win 10 and recovery partitions on drive 1
Option 2- Delete the Win 10 partition on drive 1 and clone the Win 11 partition from drive 0 to the win 10 space on drive 1. Clean drive 0 to be used 100% as data drive. I like this because it the partitions will be on the correct order.
Do you see any problem with option 2?

CalypsoArt · Apr 29, 2024

Megahertz said:
Please confirm that drive 1 has Win 10 drive 0 has Win 11.

How do I do that? I thought Disk manager would have that info somewhere, but it doesn't.

Megahertz said:
Did drive 1 came from another computer (Dell, HP etc)? If positive, was the original OS Win 7 or Win 8?
You didn't run reagentc /info

This machine MSI GS75 Stealth has these m.2 slots
1x M.2 SSD slot (SATA), 1x M.2 SSD slot (NVMe PCIe Gen3), 1x M.2 SSD Combo slot (NVMe PCIe Gen3 / SATA)

I believe the Win 10 was in the first NVMe slot. If I remember correctly, I bought the Samsung 980 1T and installed it in the second NVMe/Combo m.2 slot. I think I installed Win 11 on that one. But I don't know which drive that is 0, or 1.

I like option 2 as I want the second drive to be only data. It seems the first priority is to discover which drive is which?

~~Pardon my ignorance, but in your instructions above, reagentc /info is after Exit which take me out of the CMD window. Where do I run that command?~~

Figured it out.

antspants · Apr 29, 2024

CalypsoArt said:
How do I do that? I thought Disk manager would have that info somewhere, but it doesn't.

If you click on the drive in Disk management, in properties under the VOLUMES tab, isn’t it all listed in there?

Megahertz · Apr 29, 2024

When you took the Disk manager image (post 5) were you running win 10 or win 11?
Boot to Win 11. Open explorer. Does C: has a label or it is the D: drive that has the label Windows?

Open a CMD window as administrator and type:
diskpart
select disk 0
list part
exit
Please post the results here

aubergine · Apr 30, 2024

CalypsoArt said:
If I remember correctly, I bought the Samsung 980 1T and installed it in the second NVMe/Combo m.2 slot. I think I installed Win 11 on that one.

So drive 0 has Windows 11.

And reagentc /info shows that WinRE is enabled, and its location is in partition 2 - C:\Recovery\WindowsRE

Just create a new EFI system partition (see post #4).

CalypsoArt · Apr 30, 2024

Megahertz said:
When you took the Disk manager image (post 5) were you running win 10 or win 11?
Boot to Win 11. Open explorer. Does C: has a label or it is the D: drive that has the label Windows?

Megahertz said:
Open a CMD window as administrator and type:
diskpart
select disk 0
list part
exit
Please post the results here

CalypsoArt · Apr 30, 2024

aubergine said:
So drive 0 has Windows 11.

And reagentc /info shows that WinRE is enabled, and its location is in partition 2 - C:\Recovery\WindowsRE

Just create a new EFI system partition (see post #4).

Thanks for your efforts, and pardon my fears. (I just got this machine running again)

The instructions in post #4 are a bit intimidating for me. I'm reticent to delete boot (EFI) before being able to create one one the C: (disk 0) drive. I'm fearing I'll fail to make one and the machine will be dead. Also, I don't have a USB Win11 boot drive and what is BCDBOOT?

CalypsoArt · Apr 30, 2024

Again, thanks for the responses. Just so I'm expressing clearly what I was hoping. Ideally, the machine would boot from the Win11 drive, C: on Disk 0, I'd reformat the Win10 D: drive partition on Disk 1, and have the E: Drive partition expand to encompass that new free space.

It has been several years since I did this kind of thing so I'm being extremely cautious as I can't afford to kill this machine again.

Megahertz · Apr 30, 2024

As it is now, the Win 11 needs the win 10 drive to boot.
The instructions aubergine gave on post #4 is to create a EFI partition on drive 0 and bcdboot is to load the boot manager on it
I will simplify the instructions. Boot from win 11, open a CMD window as administrator and type:

diskpart
select volume c
shrink desired=100
create part EFI
format fs=fat32 quick label=EFI
assign letter=U
exit
bcdboot C:\Windows /s U: /f UEFI

Now you should have one more partition (EFI) on drive 0.
Shut down and remove drive 1, enter BIOS and set the priority boot drive to Windows boot manager on drive 0.
You should boot now from Win 11 drive without Win 10 drive.

We will be ready to transfer win 11 to Win 10 drive as discussed on post #8 - option 2

CalypsoArt · May 1, 2024

Megahertz said:
As it is now, the Win 11 needs the win 10 drive to boot.
The instructions aubergine gave on post #4 is to create a EFI partition on drive 0 and bcdboot is to load the boot manager on it
I will simplify the instructions. Boot from win 11, open a CMD window as administrator and type:

diskpart
select volume c
shrink desired=100
create part EFI
format fs=fat32 quick label=EFI
assign letter=U
exit
bcdboot C:\Windows /s U: /f UEFI

Now you should have one more partition (EFI) on drive 0.
Shut down and remove drive 1, enter BIOS and set the priority boot drive to Windows boot manager on drive 0.
You should boot now from Win 11 drive without Win 10 drive.

We will be ready to transfer win 11 to Win 10 drive as discussed on post #8 - option 2

When you say remove drive 1, do you mean physically remove it from the computer? I'm loathe to disassemble the machine again. Further, I believe the current drive with Win 11 is a newer and faster and think I'd like to keep it there. Where do I find BCDboot?

Megahertz · May 1, 2024

CalypsoArt said:
Further, I believe the current drive with Win 11 is a newer and faster and think I'd like to keep it there. Where do I find BCDboot?

Execute the commands above. First the Diskpart and then BCDBoot.
BCDBoot is a system tool file.

CalypsoArt · May 1, 2024

Yay! Followed the instructions:
Created the EFI partition as described
Ran BCDboot
Shut down and went into the BIOS. Initially did not see the Samsung drive listed in the boot order. Eventually found where to select the drive to put it into the boot order and now the machine is starting up directly with Win 11.

Can I use Windows Disk Manager to expand Data E: to encompass the other areas of Disk 1? I've done something like that before, but I think I used the Acronis software tool that came with a Crucial drive when I bought it.

Megahertz · May 1, 2024

Windows tools only allow to extend a partition to the right.

As you have 4 partitions to the left of E: and one to the right I would clean the drive, create a new partition and restore E: to the new partition.
or
You can delete the 4 partitions to the left of E: and create a new partition. Delete the partition to the right of E: and extend E: (easy task)
or
You can use a better disk manager like Minitoll that allow you to extend a partition to the left using an unallocated space and also to the right using an unallocated space.