Use plenty of padding (rags) when trying to pry or pull them off.
I know...not what you wanted to hear, right?
There is more than one way to skin your bird. Each has its' advantages and dis-advantages. I have:
-Lifted up (pried) the edges using screwdrivers or flat stock...both metal & wood
-Grabbed the head with channel locks and pulled
-Wiggled the whole assembly by hand...it all depends on how 'stuck' they are.
I personnally have not used the specialty tool for doing this, but have read more than one magazine article where they tried the tool and ended up chipping paint. Did they know how to use the tool? One would think (hope) so.
Start with covering the area with a layer, maybe two, of painters' tape. Then get some terry-cloth or other thick rag material, and place it between your tool of choice and the surface area you plan to use your working force on...be it the sheet metal and pry bar/ screwdriver, or the wiper arm and a pair of pliers. This reduces the potential of damage by 50%...that statistic I just made up.
You do know there is a spring loaded clip, or keeper, at the base that also has to be held out while getting it started off the shaft, correct? Good...just making sure.
Side note:
A little anti-seize on the shaft before re-installing is a good idea, should you need to remove them again...Rarely does one get them positioned 'just right' on the 1st attempt.
Maybe you can take photos and post them and a narrative back on this thread as to what worked for you? That way others could benefit from your work.
Good luck.