Hi, and welcome to the forum. I'm sorry but I'm really not fully understanding your question. Choose which of the following scenarios applies to you. If neither of these scenarios apply to you. please report back.
Procedure 1 - On the log on screen you have two user accounts with 2 different user names & you want to remove one of them
1. Log in using the old account and password. If you have personal files you want to save within this account, copy (not move) them and then paste the files to a flash drive.
2. Go to settings-accounts-family & other users. Under 'other users' you should see your second (new) user account.
Verify that the account is an administrator account. If it IS an administrator account, skip to step 4. If it is NOT an administrator account,
do step 3 first.
3. Click on the account name and select 'change account type'. Change it to administrator.
4. Log out of the old account and log in to the new account.
5. If you saved files to a flash drive, copy and paste them into you new account.
6. Go to settings-accounts-family and other users. There, you should see your old acct, Select it then click remove.
Restart. Now on your login screen you should have only the new account.
Procedure 2 - On the login screen you have 2 user accounts with same name
1. In search box type netplwiz. In the search result select "netplwiz run command"
2. Uncheck the User must enter a user name and password to use this computer, select your user name in the list
and click Apply
3. Type your password (twice) and click OK twice to close all windows.
4. Restart. It will automatically log in to windows. Log out and verify that the duplicate user name is gone from the signin screen. If it is still there
go to settings- user accounts-signin options-turn off the Use my sign-in info to automatically finish setting up my device and reopen my apps after update or restart. Restart computer.
5. If everything is in order at this point, and you want to be automatically be logged into windows every time you can stop.
If you want to have to enter a password, do steps 1-2-3-4 again, except check the box
User must enter a user name and password to use this computer, select your user name in the list
and click Apply
3. Type your password (twice) and click OK twice to close all windows. You will now be asked for a password at login.