Uninstalled Avast, but it still shuts down Windows Defender

I've been experimenting with various AV programs. I had installed Avast (free) as a trial, then decided to uninstall it. I used iobit uninstaller. Then I wanted to make sure WD was back in operation but saw the message that Avast was still in control. What can I do to get WD back into normal operation? Does it require going into the registry, which I'd like to avoid? There must be a vestige of Avast left over.

I use Revo uninstaller on my other laptop. Revo vs iobit...are both equally good or is one better, in your opinion?
BTW, I think Avast is a good program; I'm just experimenting.

The same thing happened to me last year. The Avast Removal tool did not work for me, and I had to use Iobit and do the Powerful Uninstall to get rid of all traces and leftover files from Avast. There were a few Avast files that appeared to be innocuous but apparently if they were still in the registry it was enough to stop Defender from running. Defender kicked back on immediately after the Powerful Uninstall was completed. I tried the Revo free uninstaller but it did not work nearly as well for me as Iobit Free. Iobit is easier to use and has more options for completely removing unwanted files.

I tried several different AV's last year and the removal process on all of them was difficult. It borked my laptop and I had to use Windows Fresh Start to get everything back to normal. I have been using Defender and MBAM Premium ever since then and will not change to anything else. Defender works very well.

Did you restart your system ?

Also, may want to use regedit to manually delete entries and check your drive for folders.

Thans, Dalchina (and others). I ran the Avast removal tool just now and WD appears to be back in operation.