Deleting app data/cache in ios5

How do I delete app data/cache on ios5? My husband plays "clash of clans" on his iPad and he loaded it onto my sons ipad1 (with ios5) And signed him into his game. Well he realized that my son playing on his game, that he is well involved in, is not a good idea and wants to start the game fresh on my sons iPad but it is not working. We deleted the app entirely and "re-purchaced" it on a different appleID and used a different appleID on the Game Center and when we load the app, it is still connecting to my husbands game. How do I delete the app data so that it forgets my husbands game and will start anew?