Alright thanks for the tips if he does it one more time ill delete his clash and hide his phone.
EDIT: ill try to get my account off his phone if possible. If that doesnt work then ill tell my parents. Please close the thread as there is no longer any need for it.
Impossible to delete without factory reset. If you were older you could coerce him to back-up data and factory reset, if not then at most you could simply tell your parents