Set Gmod competely to default

Okay, so you may have seen my thead on crashing issues in gmod, so I want to make my game completely brand-new like. I tried reinstalling the entire game(deleted folder and the .gcf file), but after reinstalling the game still boots up with the same graphics settings and directX-level 81 I had set before.

How can I make it FOR SURE 100% brand-new default settings.

I think it was -configdefault in launch options