OK, yeah they sometimes resist a bit.
The little metal tangs may have rusted to the housing.
I would just try some more rocking back-and-forth and maybe some twisting. They do not twist out, but are just clipped in with three or four metal spring tangs.
When in perfect shape they pop right out.
I don’t want you to break one, but you may have to apply some force. At the very least just fiddle with it a bit rocking back-and-forth.
Then again, maybe somebody who’s done it more recently can correct me if I’m wrong. If there are alignment notches, or if they do twist out, I’d hate to make you break one by trying to rock it.
It’s been a very long time since I’ve had to replace one, and I might be thinking about another vehicle.