I used avastclear. Before installing avast, I uninstalled everything else
I used iobit uninstaller only. I could also use geek uninstaller to uninstall avast.

Now I temporarily use secureaplus and kaspersky antiransomware
I may comeback to avast after a week to see if there is any change
but with my current setup, I can see a significant boost in my laptop performance. Avast 2017 has been too heavy compared to version 12. Most noticeably the boot time