Daughter bought a 2012 Prius V that came with only one key fob. Although I realize the risk is low, I don't like the idea that another working fob could be floating around out there. I'd like to deregister the missing fob to render it unusable (and, ultimately, add another fob). I have Techstream. Of course, my big concern is accidentally deregistering the fob she has when I attempt to deregister the missing one. Can someone walk me through the process to do this safely? Thanks.