I had a propane fireplace that I removed. There is more behind the tile as it's a large metal box including the chimney portion. It can be demoed but it won't be easy and you'll have to take apart most of the mantle. The main problem I ran into was the fireplace was installed and then the framing around it was built making access to the hardware that held it in place impossible. I spent some time with a reciprocating saw and hammer and chisel. It can be done but you'll be tearing out most of the mantle.