Removing Mushroom

I was given a plug with some polyps on it and within the polyps is a sponge. Since I have had this plug the sponge, which I was told is a black sponge, has almost tripled in size. This is in 2 weeks. I was also told that a black sponge is very invasive. It was mostly removed before putting it in my tank but obviously not all the way. So I asked my friend how I should remove it and he told me....now here is where I get to my question. This plug is apoxied into a hole in my LR that I can't get out. I would like to take it out so I don't drop a small piece in my tank. Is there any way to remove a plug out of epoxy in a hole or should I just take out the LR? The LR is on the top so I wouldn't have to move anything else!:-/:-/

 

I would just take the rock outside the tank and deal with then, it isn't safe to do inside the tank.