Usually I just remove the drain cock if there’s a floor drain close by however, if there isnt a safe place to drain the water then you’re up against a wall. I have used a shop vac on the cold water inlet to drain water heaters before. Its a pain having to dump the shop vac bucket numerous times til the water level is down, but if it were easy anyone could be a plumber. lol
Take the drain out and install a nipple and a full port valve and use rod are something to stick in there and loosen up sluge, you can try it with CW stop on but be ready to shut off press.