you remove the drain plug!
on the right rear of the oil tank, you will find a 1/2" drain line going straight down to a nipple on the frame, just inside the frame, inboard of the exhaust pipes and just aft of the transmission side cover.
if you look under the frame at that spot, you will find the drain plug.
when changing the oil, ensure the engine is at operating temperture before draining the oil. (it doesn't hurt long.....)