How to get parking brake cables off rear axle??

easiest way is to cut them off and replace with new ones. Otherwise, the end that goes into the drum backing plate is a flare / finger type end. when you push it through from the back side, the fingers compress, then once all the way in, they open up again not allowing the cable to be pulled out. You can try to compress them carefully and get one edge out of the hole then keep working your way around. It is tedious, but I have done it...But on the last project, I cut them with the dewalt and went on with my day... haha

That is usually the easiest, quickest way.