How to remove Adobe Illustrator installation files

I tried to update Illustrator cc, and the update failed. Based on advice I've seen on this site, I uninstalled Illustrator. But this apparently does NOT delete the folder named "Adobe Illustrator 2020" in C:\Program Files\Adobe. Further investigation reveals that the root cause is an inability to delete C:\Program Files\Adobe\Adobe Illustrator 2020\Support Files\Contents\Windows. I can neither delete this (even with Administrator privilege) nor look inside it.

The inability to delete this folder seems to be the root cause for why I can't install the latest version of Illustrator 2020 after uninstalling it with the Windows uninstall tool. I remember dealing with this a year ago while updating to Illustrator cc 2019, but sadly, I didn't write down what I did because I assumed (incorrectly) that a problem this egregious would get fixed in the next release.

So if someone can help me delete these files so I can re-install Illustrator, I promise to write down the steps so I can use them with the next update.

{Renamed by MOD}