Your pictures are too small to make out detail. I'm not familar with drum traps, but I have done a fair amount of remodeling over the last 50 years so here are a couple of thoughts. Often things are installed then later other things are built over/around them with no thought of ever removing anything. You ofter have to be inventative and even destructive at times. Cut the hole larger, take it out from below, disassemble (even by brute force) It went in someway that is now blocked, so figure what is blocking it and what you have to do to remove the block. That's not very specific, but little in remodeling is. My wife cringes when I ask her where my crow bar is. It usually something is going to get torn up big time.