I don't know your model, but I have a 2011 Berkshire 390BH. I was told when I de-winterize my unit to drain all of the antifreeze out first from the main water system, then drain the antifreeze out of the ice cube system. When my unit was winterized, they disconnected the ice maker tube to prevent the RV antifreeze from going into the unit and making pink ice cubes.
I have circled the tube with the pink antifreeze in it. I have also circled the part with the hose disconnected.
Also when they winterized it, they unplugged the electrical connection to the unit with the hose that was disconnected. I was told to drain this unit using a patch cord with two connectors that needs to be plugged into the area at the top of the next picture which is also circled. (you would need to unplug the existing connections there to drain the tube).
After you drain the hose, you would reconnect the disconnected tube to the unit. I hope this helps.