Turn off multiplayer activity or friend requests. Go to Settings > General > Restrictions.
If the switches are dimmed, first tap Enable Restrictions at the top.
Keep it friendly. To report offensive or inappropriate behavior, tap Friends, tap the person’s
name, tap in the upper right, then tap Report a Problem.
Game Center settings
Go to Settings > Game Center, where you can:
Sign out (tap your Apple ID)
Allow invites
Let nearby players find you
Edit your Game Center profile (tap your nickname)
Get friend recommendations from Contacts or Facebook
Specify which notifications you want for Game Center. Go to Settings > Notifications >
Game Center. If Game Center doesn’t appear, turn on Notifications.
Change restrictions for Game Center. Go to Settings > General > Restrictions.