Nuvo Lighting 60/3107 "Kingston" Flush Mount Ceiling Light How do I undo this fixture to remove the dome! This is such a pain

The large finished nut at the bottom of the globe should unthread off a nipple, and allow the globe to drop.

If this nut just spins, then possible the nut is on the threaded nipple too tight and the nuts up inside the fixture that hold the nipple tight to the fixture frame are loose.

If that is the case, and cannot unthread the bottom finished nut, then you may need to break the glass.