I'm trying to remove a 1 1/2 inch to 1 1/4 inch adapter off a 1 1/2 inch metal T adapter. There is no where to grip it or turn it. The only thing that I noticed was a 'slot' in the front where it looks like you would put a chisel and hammer it off (see red circle below). Has anyone ever seen one of these. The house was built in the late 50's. Any help would be greatly appreciated.