You have to pull it straight up as there are little grooves within the wiper arm and the "stub", that connects to the wiper motor. Once you lift it up about 1/8", you'll notice that the little tab you are describing will need to be pulled out of thr way to clear the stub. Move it to the side and continue to slide the arm STRAIGHT up. It's hard to do because I'm sure you don't want to chip your paint. It probably hasnt been removed since it left the factory so its on there real good.