help now!

i went to the menu to see what was there, i clicked "online staff" but i fatfingered and accidentally pressed "give all achievements". i want help undoing this!

I was playing zombie escape with a couple people then I was about to win a game and was banned I was furious and didn't know what to do so I came to your guyses website and wondered if you could help me I need you to respond as fast as possible please and thank you for your time if you need me...