To sign out of Game Center, open the Settings app and choose Game Center. To turn off Game Center, select Settings > Game Center.
Go to Settings > Apple ID Profile > iCloud and select Manage Storage. nLook for the game in the list of apps that iCloud backs up data for and tap it. Select Delete Data, which will remove all data from all Apple ID-linked devices. A warning appears asking you to confirm the deletion; do so by tapping Yes.
Select Apple ID and Password & Security from the drop-down menu in Settings > Apple ID. Check the box next to Apps Using Apple ID. You can look through the list of apps you’ve signed into with Apple, choose one to view its information, and then remove it by tapping Stop Using.