Currently Being ModeratedAug 17, 2013 6:38 PM (in response to Soleil_2772)
You open the Game Center app, sign in and swipe across the game. You'll be given the option to remove it from your device, so read that pop up and make the choice you want to make.
Unfortunately, HayDay may pop back into Game Center whether you want it there or not. Several of my games go back into Game Center even after I remove them. There's not much you can do about it. It's like APple has made Game Center participation mandatory....if the game is a Game Center game, you sign in (The only exception I've noted are very kid centered games, ones meant for elementary school kids)