I agree with this person. If you need to get out of your agreement, do it. Cancel your lines, port your numbers, and pay the ETFs. More than likely you're "done" because of something you don't think you should be responsible for..like your teenager "not" using the internet on their phone EVER because they "don't know how" or calls to another country made by someone you let borrow your phone.
Here's a tip for the future. If a phone is in your name, you are responsible for EVERYTHING that is done with it. It doesn't matter who did it specifically, you ARE responsible for it.