This must be done with extreme care. Use a Dremel tool with one of the little cutoff wheels and cut a slot in the seat lengthwise on 2 sides about 1/8 to 3/16" deep. Insert a flat blade screwdriver into the slot and twist the screwdriver. DO NOT PRY! The seat should pop or break along the cut. Repeat on the other side. You may wind up only removing half the seat. In that case, go back to the heat to soften the glue. The seat isn't insulating things anymore so it should come loose pretty easily.