Got it off, finally. There was no screw. And there was also no clip, at least not the kind that I was expecting.
The plastic housing is attached to the metal bracket beneath (OK, that was obvious.) I stuck the screwdriver in the top hole (picture #3) and started to pry on it quite hard - pushing the tiny flat bladed screwdriver downward and using the metal bracket beneath as leverage. The plastic housing has edges on each side (Right and left) that grip onto the metal bracket that is glued to the windshield. Basically you have to pry the housing off of the bracket. It's on there good. The first time, the screwdriver popped back out. With enough force, the housing starts to lift off of the metal bracket slowly going away from the windshield. The housing basically hinges on the bottom of the metal bracket and the top pulls away first toward you.
Anyway, what a PITA. Hope this helps someone else do this nightmarishly simple task.
