Like rockfordroo said, there is probably no drain plug, you pull the anode rod. The rod may appear damaged but it may have plenty of life left, it is supposed to look corroded. My real reason for commenting is to warn you to turn off the electric element at the tank during winterized state so it cannot be accidentally turned on with no water inside. Also, you should wait a while to let the water cool if it has been on. The water may only gurgle out at first but if you pull the pressure relief valve it will pour out fast, stand to the side when you pull the relief valve or you may get wet.
2016 Cherokee 264L
2013 GMC Sierra Denali
EAZ Lift 1000 WDH w/Sway Control
2016 Nights Camped: 20 Trips: 7