Someone mentioned an allen key, which just reminded me of when I had to take my rotary table apart.
No way could I see how to remove the top part from the base, but it turned out that there was a tiny Allen screw holding both together, which could not be reached by a standard Allen key, no room to get the key in place.
The only way was to grind down a key to almost nothing to locate the screw, which could not be seen [maybe you were not supposed to see it, who knows ? ]There may be more stupid ways to do things, but method of holding two simple parts together must be high on the list. The table in question is a HOMGE.
Might be worth looking to see if your job is similar.![surprise surprise](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)