Use a fine-tooth hacksaw to cut through the seat hinge and the bolts. Then simply replace it with a new toilet seat. A new toilet seat is extremely inexpensive and the attachment bolts are no longer made of metal. Most all of the manufacturers are using nylon nuts and bolts – no rust there. By the way, there is now a toilet seat on the market that is removable at the flick of tow knobs. They make cleaning a breeze and the quality of the product is incredible.