How do I delete Game Center app and data

When you sign in with your Apple ID, you will automatically be signed in with Game Center. To delete game data, go to settings>your name>iCloud>manage storage and click the games you want to delete. This will remove your Game Center data across all of your devices.

For the hack: what makes you think that you're hacked? iPhones are very difficult to hack, if you have not jailbroken your iPhone, you're most likely not hacked.