How can I remove all traces of McAfee under Windows 10?

It is well known that it is pretty hard to remove McAfee from a computer once it has been installed.
Unfortunately my new Windows 10 PC came with a test version of McAfee installed.

I uninstalled it with Revo Uninstaller, which should be more thorough than the Windows uninstaller as far as orphaned files and registry entries are concerned. So I thought every trace was gone.

But this morning after my PC booted I got this message:

I used Everything to find remaining files, and indeed there were some, esp. the following .exe files:

McAfeeSecurityStartup.exe
McAfeeSecurityFT.exe

Trying to delete them doesn't work.

Also, the Registry still contains myriad McAfee, which I started to delete (after making a backup). I gave up after I found that several keys wouldn't let them be removed. I tried this running Windows in Safe Mode as well, but I still couldn't remove files or Registry entries.

One possible explanation could be that there is still a McAfee service running, but I couldn't find it.

Next thing I tried: The McAfee Removal Tool. Files are still there.

So I've run out of ideas. How can you remove all traces of McAfee from your computer?

To eradicate all startup entries belonging to McAfee, use the free autoruns.

Go on the Everything tab, then use the menu Entry/Find with the string "McAfee". You may delete (carefully) any entry that it finds, then reboot to verify.