Yes, you have to drain your Delonghi portable air conditioner. Although not all portable air conditioners need to drain, however, the Delonghi portable air conditioner is designed in such a way that users will have to drain water. The unit makes use of water it accumulates from the prevailing humidity within the room to cool down the condenser which is usually the most heated up part of the entire AC components. When you drain your Delonghi portable air conditioner, it will improve the overall efficiency of the unit as a whole.