Where is the oil drain plug on my four wheeler?

Its a Honda TRX 400EXWhere is the oil drain plug on my four wheeler?
All drain plugs are located as low as possible on the bottoms or side of the engines. It may be a square plug sticking out of the side or bottom that you can remove with a crescent wrench or equivalent open end wrench, or it can be a round plug flush with the engine housing that you will need an allen wrench to remove. Take a shop towel and wipe the dirt and grime from around the bottom of the engine, you will find it.Where is the oil drain plug on my four wheeler?
There is a hole in the frame under the engine.
At the bottom or side of the engine.