Solved Default-App: How to delete?

Hey!

I'm getting in a total crisis right now. Thanks to Windows I cannot recognize anymore how to disable a default app.
A few years ago I knew how to search for default file extensions and just delete it to not let them open again with a default app.

Because:
My problem is I accidently run an "unknown" file with a program and I've clicked on "always" open with that.
Now that file opens up always with that program (app) what I don't want.
:.-(

I was searching the internet but there's no help anymore!
Microsoft drives its new way to let the customers as leftover idiots. That makes me sick.

Here's what I mean:

But I want the complete opposite which is (of courseee) absolutely no explained.

So, how I delete a default app in Win 11 ?

Thx in advance!

Sincerely!

settings>apps>default apps>toward bottom select choose apps by file type. Find file type in list and change to what you want.

You can also set all file type associations to default or Brink has provided regfiles for the most common file types. Reset and Restore Default Apps for File Types in Windows 11 Tutorial

Because appids are involved there is no straightforward way to solve it for an unknown file type using the registry. This article shows you examples and explains why.

Hey!
"Find file type in list and change to what you want." That's not what I wanted.
"all file type associations to default" That's what I meant with "stupidity of Microsoft". In the past it was possible to set just one file back to "do nothing" (deleting app connecting to file ext.). But the option is gone or missing or whatever.

The only option in regedit worked for me:
"Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\ ......."

Thank you! Problem solved!