That's a tricky question you are asking. I would think it would depend how you mean "take it away from you"!
If you are asking about whether or not they can GROUND you from that phone you bought... absolutely they can. It doesn't matter who bought it. If you don't follow the rules, they can ground you from it. Just like as an adult, although I pay my fees for my Driver's License, if I violate the traffic laws or don't pay child support if ordered to do so, etc., they can suspend my driver's license regardless of the fact that I paid for that License!!!
Now, if you are asking instead if you go out and buy a phone and they think, oh, wow, that's a neat phone, I would like to have it for myself... now that one.. not sure about the laws specifically, but thinking logically, that just wouldn't be very nice and I would think it would be wrong.