We just moved into a home that has had a wood stove in for about ten years. We noticed that air flow wasn't great and upon speaking to someone at a store they said that there is a cover plate behind the area where the ash pan is. It was/is supposed to be removed upon installation. Sure enough it is still on and there is even a sign on it that says to remove for room air. How to I get it off? It seems as though I would 'punch' it inwards but it looks as though it is attached (maybe soldered) slightly at the top and bottom of the circle. I don't want to go bashing it with a hammer. What is the best way to remove this plate? Picture attached.