Continuing GPS Issues

We have got to figure out how to prevent Brother from tracking our tablet's GPS.  Surely there is something we can do to keep him from finding us.  We hopped to the library today and immediately got hit with texts demanding to know why we were there, and why were we in there for longer than it would take to return something, and were we checking out books, and if so to drop them immediately and to leave at once.  Then we went to a second library and the texts got worse, demanding to know why in the world we would need to visit two libraries in one day and how he was definitely sure we were checking out books and to stop at once.  We're just thankful that the GPS doesn't show what section of the library we were in so Brother can't know for sure what books we were borrowing.  We have got to do something to block him.  He's getting seriously annoying.