Here are the instructions put together by Avast
to get rid of virtually all 3rd party antivirus programs
Prior to installing avast!
Uninstalling third-party antivirus software (Removing your Current AV)
https://support.avast.com/index.php?languageid=1&group=eng&_m=knowledgebase&_a=viewarticle&kbarticleid=574
Bookmarked it, Bob. Good stuff.
Agree but think that the removal tool for avast! should also be included since some of the problems we run into deal with and can only cured through a fresh install which
would require the removal of a failed avast! install, 
It would also then require the posting of only one link to cover all circumstances.