How to Fully Remove Avast?

My mother had Avast Internet Security installed with a license(I think, I can’t really remember). I need it uninstalled.

OS: Windows 8

Steps I have tried:

Downloading Avast’s Uninstalled (Avast Clear)
Running it in Safe Mode. Leaving the directory default.
Choosing Avast Secutiry. Also chose free. Also chose pro.

Once I boot back, there are still remnants of files leftover.
For example:

folder: amd64_avast.vc140.crt_fcc99ee6193ebbca_14.0.25325.0_none_586e9d411a1940c6 in C:\Windows\WinSxS

folder: x86_avast.vc140.crt_fcc99ee6193ebbca_14.0.25325.0_none_a01bd4182e9569cc in C:\Windows\WinSxS

more of the above.

folder: avast! sandbox in C:\

file: amd64_policy.14.0.avast.vc140.crt_fcc99ee6193ebbca_14.0.25325.0_none_4b5d1834d3072800 in C:\Windows\WinSxS\Manifests

A lot of the ones above.

These folders: amd64_avast.vc140.crt_fcc99ee6193ebbca_14.0.25325.0_none_586e9d411a1940c6 in C:\Windows\WinSxS, I changed owner from TrusterInstaller to Admin in order to delete them.

I have also tried Revo Pro. No luck. I have also tried reinstalling Avast Free and trying Avastclear. Should I perhaps try the trial for internet security instead?

Look, this has been quite frustrating. I need windows defender to work and it won’t because I assume it still detects traces of Avast. Help get rid of Avast, or at least enough of it to allow windows defender to take over. Thanks you for any help.

Even a simple removal of Avast via the Programs and Features function
starts Windows Defender.
I agree with you that the Avast Cleanup tool needs to do a better job but,
it doesn’t prevent Defender from starting if it’s used.