Take her to a doctor to remove it.

He should take a v shaped "clamp", spread the ring to get the ball out and then it should come right out.

Otherwise, sterilized needle nose pliers will do the trick. Those tension rings can be a ***** to remove.

On a side note: You need to talk to your daughter. What is a thirteen year old doing with what is considered a sexual piercing? Who did this? Did she get it at a piercing party?

You need to open the lines of communication with your child and know where she is and what she is doing, before she comes home with a FTW tattoo on her hand or something.

Edited to add: Those telling this woman to take her daughter to a piercing shop - that's a no go. One of the reasons it is illegal to piece in this area under the age of 18 ANYWHERE is because this is considered a sexual piercing. A piercer and a shop can be sued if they touch her daughter's breast or even see it for child sexual abuse (seriously). No place that does piercings will touch her because they are all aware of this, and the horror stories where people can be sued for this very thing. She needs to take her daughter to the family doctor.