Now here is a software that most people do not know about. The Avast Uninstall Utility is a software that uninstalls Avast Antivirus completely from one's system.
There was once a time when my Avast Antivirus did not want to update, i tried installing a new version but it was rejecting it. I also tried uninstalling to no avail. then i came across this.
Now how to use it.
Download Avast Uninstall Utility then restart your system in Safe Mode. Locate the downloaded file named aswclear.exe and run. Follow the instructions and Avast will be successfully uninstalled.