Can't help you with that but there are quite a few people on this forum that can if you can wait awhile for their reply. Welcome and post some pictures of your boat and tell us a bit about it and yourself.
The button on the outside of the rail will release the ball. The plastic unit is not designed to be removed easily. Usually releasing the front will let it fold up to store. To lower flat against the seats just pop out the rear legs and fold up, usually a second set of hands is helpful. Hopefully this helps??!!