If the ring has been on there for years, it could be a bear to pop off. Like Dave said, get a paint can opener, you might have to grind the end thinner to get enough bite on the ring to pop it off. Get some lubricant inside the bottom of the ring somehow, you can always clean up the mess later. Pull directly on the bottom with a sharp jerk! They were hard to get off when they were new. I had one once where a co-worker squeezed the sides as I pulled on the bottom to get it to pop. PJ