70 Dart Bench seat headrest removal

Does anybody know an easy way to remove these for reconditioning? The seat I found is mint, but the headrests slide up and down a few inches and then lock. They don't come all the way out. They feel as if only one pedestal on each side is locking them in place. Is there a detent of some kind that has to be pressed to release them?

There the funky '70 only small headrests that actually look like armrests.

Thanks,
Steve