ON a 1969 any number of modifications might have happened. Three common types:
Most dinettes have a table with a folding leg. The table top is attached to the wall with two fasteners at the edge of the table that look a little like a foot locker's locks only inverted. Under the table there is a U shaped and a brace/hinge that controls the height and drop of the table down to seat level. Fold the leg up under the table (there is some kind of release on the leg), then tilt the free end of the table slightly upward to pull the two tongue hooks out of the wall receivers. Once free just pull the table top toward you and gravity will do the rest.
Some dinettes have a free standing table with a piller leg. The table can be lifted off the piller, then the piller can be removed from the base and the table (a) a second piller that's the same height as the bench can be inserted or (b) the table simply rests/nests on the dinette seats.
A few have hydraulic lifts - think of a chair in a beauty shop or office. Use the lever.
If none of that makes sense post pictures. Someone will figure it out.
Today is a gift, that's why they call it the present.