Can't deauthorize Crysis 2. Please help!

I just bought a new graphics card. geforce gtx TI and installed it. Problem is when I did, it didn't want to start Crysis 2 so it had to authorize . I plugged my old graphics card in there and it starts fine. However I can't seem to deauthorize it which in other words unistall it. Please help me, I am getting really annoyed by this. Any of you had this problem and if so, how do you fix it?