I finally got them off. I held the bar vertically with the bottom end of the bar on a table. I stuck two flat head screwdrivers under the edge of the bottom cap, the screw drivers were on opposite sides of this cap. I had a partner hold the screwdrivers down with both his hands, and I pulled up on the bar. Came off pretty easily with that technique.

When I used just one screwdriver it poked a hole through the cap.