Gallbladder out 3 days ago. 4 incisions. Dr took 3 bandages off, my belly button still has gauze, big clear square bandage. Do I remove that?

You can remove it. Remove it, wash it well with soap & water, rinse, dry & if dry no need to place any more dressing.
After surgery. I think you could, espcially if the bandage is wowrn out. Dont forget to wash your hands before removing and you could apply some peroxide and let it dry to the air before puttinga new one.