How do you completely drain an above ground swimming pool when it has already been closed down and disconnected?

siphon the water out with a hose. You can even get a siphon going with a pool vac hose. Just get the whole hose full of water in the pool, keep one end of it submerged in the pool put yous hand over the other end so no air can get into it lift it over the edge of the pool and when it is below water level let go. the water will just pour out until there is no more water in the pool.