If you do the following you will remove the smell of the hot water. This has nothing to do with the valves for winterizing. Geez…. Well do turn off the water pump or dis-connect from city water. Open a hot water valve in the camper to relieve pressure in the line.
The hot water heater is a simple fix. Drain it from the outside. Squirt bleach into the drain hole several times with a kitchen baster. Screw the plug into the hole and turn on the pump to fill the hot water tank. Let sit for a day and then just use it till the chlorine smell goes away. Showers will be chlorine fresh for several days.