Answers to latest suggestions:

1- I use CCleaner regularly to clean up the registry; I use the free version which I do not think has an option for dealing with the context menu. Now, even if the...

I think I agree 100%.
Unfortunately I have to keep using Windows, otherwise I would have left the registry and all related benefits behind a long time ago.
I am grateful for your consideration of...

Maybe so, but unfortunately Powershell skill is not something I am familiar with or could be justified to learn for this unique purpose.
Besides, I might not want to remove the application from the...

My question is how to dis-associate (un-associate, remove) one option from the windows-explorer "open with" menu.
For ex.:
Windows 10 -> Explorer -> file.mp4 -> "Open with" gives me these options:...