How to prevent Sprint Family Locator from tracking iPhone 4?

I have an iPhone 4 and my dad recently added Sprint Family Locator services to the account. I'm really uncomfortable with this because now I can't go see my girlfriend or do anything else without him knowing (he doesn't like her).It's not like I'm selling drugs or in a gang or something, I just want some privacy. I'm 18, but I don't want to pay for my own phone so don't tell me to just get my own account.

Is there a way for me to prevent the service from finding my phone without putting it in airplane mode (i.e.still able to talk, text, use data, etc.)? I don't have access to the account so I can't test out different things like turning off location services or mobile data, and I'm not sure that would even work as the website says it can triangulate based on cell tower distance.

I've considered turning off location services, somebody please tell me if that works. I would rather not have to turn off all of the communications functions of the phone. Thanks!

P.S. Don't give me any bullshit about it being "his account, his rules" or "what do you have to hide" because I've already thought about that and for me it's a matter of privacy and respect, not deception and secrecy.

I would try turning off the location services/gps. But they may track you by the cell towers. You may be able to gain access to the service yourself and make it so they can't track you.