Hi Cord_Moto
I am Dave, I will help you with this.
It is not easy to remove a file association in Windows 10, the trick is to create a fake program, then associate the files to that and then delete the fake program.
1
Open Windows File Explorer
On the view Ribbon (tab) check the box marked 'File Name Extensions'
Close File Explorer
2
Right click your Desktop and choose New - Text File
Right click that text file and choose rename, then change the file extension on that new file from .txt to .exe
Confirm the change
3
Right click a .xxx file, choose open with - Choose another App
Check the box marked 'Always use this app to open .xxx files' - IMPORTANT!
Scroll to the bottom and click 'More Apps'
Again scroll to the bottom and choose 'Find another app on this PC'
Navigate to the dummy file exe on your Desktop and click OK
The .xxx file will not open, this is expected
4
Delete the fake exe file on your Desktop and restart (not shut down) your PC
The file association will then be removed!