I'm trying to remove the drain/flange from a kitchen sink so that I can install a garbage disposal unit. I can not get the wide nut on the underside of the sink to turn. I'm assuming it's glued or rusted or painted into place. Is there any sort of special tool to help remove it or anything I can do to try and loosen it up? Right now I'm just using a 12 inch groove joint plier to try and remove it. It's just barely big enough to get a grip on it.
Attached is a photo of the underside of the sink