The campers I have had with a pole supporting the dinette table were just a friction fit at the top and bottom of the pole. Sort of the way that a vacuum cleaner wand goes together. If the previous owners rarely or never used the dinette bed, the pole could get jammed into the floor socket pretty tight, and be very difficult to remove.
Try this: take the table top off the pole, and grab the top of the pole with both hands. Move the top of the pole around in a circular motion while pulling up on on it. Hopefully it will loosen up and come out.
Once you get the pole out of the floor socket, the table top is typically sized so that it sets down in the open part of the “U” and the cushions will rearrange to make a mattress.
:):)