See if this helps: https://support.avast.com/en-ww/article/94
As far as I'm concerned, I use the advanced mode of Revo-Unistaller if I want to uninstall avast and I never need to delete the remaining folders or Avast Firewall Driver or ......
nb:of course the software can't delete all traces (folders and registry keys) when windows is mounted, but they are by rebooting before the session is started ,so before avast (or what's left of it) is started.
On the other hand, I have not yet tried with the new way of using the registry for the settings but as Revo has the habit of going deep into the registry for traces,I don't really see why it wouldn't do the job as usual, probably better than avastclear ? (this is my feeling from my experience so far

, I may be wrong for the new versions

)