Place a 1 1/2- to 2-pint capacity plastic tray beneath the plastic drainage hose at the base of the air conditioner, at the back.
Pull out the plug blocking the drainage hose. Water will drain out of the air conditioner into the plastic tray.
Wait for the water to stop coming out of the hose. The tank has a capacity of around 1 1/2 pints or 24 oz.
Carefully carry the tray to the nearest sink and empty the water down the drain.
Put the plug pack in the hose and switch on the air conditioner. The alarm light will turn off.