There is no law that the other parent can not take their child out of state or county, What happens, is that when the two file in court for custody, and they get custody rights, visitaiton rights and child support assigned, they can also ask that the other can not MOVE out of state, This does not apply normally to vacation and trips unless they would interfere with schedulted visit times.

So if there is no court orders in place, you need to file and get legal status of the custody of the child