Good luck attempting that! If you look through the registry for AVG you'll also see entries for Grisoft (old company name) and Avast (new owners) I have seen entries for other more obscure AVG and Avast services as well - even though Avast is not installed. There are also some obscure entries with AVG in the name but I'm not sure if they are actually for "AVG?"
Be aware that if you have any Piriform Software installed like CCleaner or recuvva etc that you may inadvertently remove them as well.
Some of the entries for Piriform fall under the Avast key sets.
And to complicate matters further it also depends on how long AVG has been installed.
Older installations have different entries for different versions as they've been updated.
