I have been having this problem for the past two months in which Avast has installed several different modules without my permission, the latest being “Avast Passwords” and this is now popping up every time I wish to check the details of custom scans and other notifications with the Avast Anti-Virus program.
I see no reason for Avast to be installing things without permission and pushing me to use products when I have no need for them and am trying to use a different product of theirs.
When you do a fresh or clean install, unselect what you don’t want. Don’t use the default install.
You’ll find help here: https://youtu.be/zHrMzThl9X0
If you used the default install, go into your settings, Components and remove the item’s you didn’t want.
When installing applications always choose the “custom” install option (if available). That way you can deselect the items that you don’t want.
I think that’s what I said. 
→ https://support.avast.com/article/96/ (Add/Remove components)