Well, I have the same question. Any way to: Quit Avast (actually really quit, shutting down its processes) and/or not have Avast run as a startup? I want to be able to electively run it when I want: say, to do a full system scan of my Mac and then turn Avast completely off. (I was a bit pissed when I found that avast’s startup is super-hard-wired: ie, its not in System Preferences|Accounts|Login Items; that would’ve been a logical place to put it.)
It’s looking like to really run it “on demand” you have to install and uninstall, which is obviously not practicable.