Beginner question

I have a tripod and will be using it with my camcorder. There are two posts on the tripod surface - one threaded and the other not. I get that I screw the camcorder onto the surface using the threaded post but how do I get it off of the tripod if the second post is in place in the bottom of the camcorder? Does that make sense? I don't understand how to release the second post in order to remove the camcorder from the tripod.

Thanks,
k