These certainly can be a pain in the aXX, right under the arm itself where it sits on the post you will see a small steel tab that goes down over the splined wiper arm post, you need a small screw driver to pry the tab open and lift the arm at the same time. If they haven't been off in a long time you may want to soak them in penetrating oil for a day. I have wrapped the arm with a rag and used a pair of pliers to remove the tuff ones but you can scratch the area under the arm pretty easy if you are not carefull. Good luck.