It appears from your post that your concern is about channel catfish and bass.
If that is your goal and if you have a decent bluegill forage base, I would start fishing the heck out of the pond to eliminate the unwanted fish.
You don't mention the size of the crappie or the bullheads. If you don't see any small ones, then they are probably providing the forage base for the rest of the fish. Are your bass stunted or just small? Are you seeing bass recruitment? It could be that the snappers are destroying nests. If your bass don't go over 12 inches and are skinny, they aren't getting adequate groceries.
I would, as Alligator and ML state, first determine goals. Then analyze the current status of the population(s). Next, build a management plan and implement it.
No way I would drain or rotenone it and start over unless you want quicker results. You'll never totally eliminate all of the problem fish but you can significantly reduce their impact. In addition to fishing, you might consider traps for bullheads and green sunfish.
