I deinstalled using the regular Windows deinstall program.
How do I deactivate Avast's self-protection mechanism?
You can deactivate it in the settings. I use the german version, because of this, I don't know, where the setting point exactly is in other versions. But look in the settings, you will find it. I'm sure.
Then deactivate the programm over the avast icon in the taskbar with rightclick (context menue).
Once I go into safe-mode, what do I do there?
Run the removal-tool in safe mode and change the version you want to uninstall, restart the PC after that.
Then install the newest version of avast! and after that reboot your PC.
Does it work now?
PS: Pondus posted the link to the uninstall utility (removal tool).
Edit:David, you're to fast for me...
