It’s easy to remove the sheet metal with a utility knife. Just force the blade in between the sheet metal and chimney flue and work your way around. All you need to do is slice through the caulk and the metal comes right off. If you plan on using your fireplace a lot – use a chimney flue top damper. They make it easy to use your fireplace whenever you want. All you need to do is pull a chain hanging from your fireplace.