I can't believe it went 3 pages before someone said it.
Seriously though, my SIL did the same thing to my BILs cell phone. She had control of his texts, listened to his calls and could tell every where the phone was every second of the day. Drop that phone get a new one from a different carrier and transfer her old number to the new phone. If that doesn't stop his stupid shit, then handle it seabass.