Generally, the table is raised vertically out of the pedestal base, and the tube disengaged from the table. If the table has been in position since 1985, it's probably corroded and frozen. The simplest solution may be to unscrew the pedestal base (which might also be through bolted to the underdeck, requiring reaching into the bilge
with a socket wrench). That way you can pull the whole assembly out of the boat
and have some room to work
on it. Which may require a lot of WD40, elbow
grease, and persistence. Once you solve the stickyness issue, you will be able to notice those little sticks of wood
around the edges of the seas that conveniently mate with the edges of the table, to convert it into a guest berth. Once you clean up the support structure, it should be much easier to make the conversion from table to berth.