How do I take the right real panel off the door to check the window regulator cable?

Also how do I change the regulator if that is the problem?

It is easy to get the door panel off. I'm assuming you mean the right rear passenger side door. At the door pull handle (recessed area) not lever is a plastic cover. Remove with a small screwdriver. Underneath are two bolts. Remove. Then carefully starting at bottom of door get a good grip on the panel and pull outward. There are several trim panel fasteners that hold the door panel to the door frame. Once panel is pulled then carefully slide over the door latch handle, up and then out. Some trim fasteners may break but you can get them at places like Autozone.

I'll see if I have a tech procedure for the regulator.