Yes you can. But it is highly discouraged since you are now not filtering any large items out of your pull which then goes into your pump and will ruin the pump.
It isn't different from an in ground pump in the case of the very small above ground pools they may be some what smaller then the average in-ground pool pump.
Unless you had the pool installed with a bottom drain there is not a drain on an above ground pool. You'll have to pump the water out using a sump pump or siphon it out using a garden hose. Please...