How do I r replace rear window wiper arm?

Wrap electrical tape around the head of the flat-head screwdriver. Use the screwdriver to carefully lift the outer edge of the protective cap at the base of the rear wiper arm. Pop the cap off the arm and set it down on the bumper. Pull the wiper fluid hose away from its connection on the wiper arm. Use care when you disconnect the hose to avoid disconnecting it from the wiper motor within the lift gate. If the hose starts to leak washer fluid, clog it by sticking a toothpick halfway into the hole on the hose. Hold the wiper arm near its base with one hand; loosen and remove the wiper arm's securing nut with your socket wrench. Remove the wiper arm from the motor's pivot shaft by pulling it toward you. Dirt and debris often build up around the joint and prevent the arm from pulling off. If this is the case, wiggle the arm back-and-forth a bit to release it.

I have followed all of these steps up until I attempt to remove the wiper arm. It refuses to budge and I have had a couple others try and pull it off also. I have tried WD40 and prying it off with a screw driver. Any other thoughts on how to get it off?

Use flywheel puller is the best way