How do I uninstall Avast Online Security add-on for Firefox completely? It messes with many webpages and I want to get rid of it completely. I cannot find the option to do so either in Firefox or in the Avast UI.
From Firefox>click “tools”>click “add-ons”>disable the AOS extension. 
I know how to disable it, I want to uninstall it completely.
Go to add remove programs, click avast/ uninstall/ change and remove the parts you don’t want.
Done, thanks.
Your welcome