While the process may vary depending on the make and model of your drone, the DJI Intelligent Flight Battery Safety Guidelines (for both the Phantom and Mavic series) recommend discharging the battery by using the aircraft until the battery is depleted.
Here are some other LiPo battery maintenance tips, courtesy of the DJI intelligent battery guide linked to above:
- Before carrying the batteries on an airline flight, they must first be discharged to a battery level lower than 30%. This can be done by using your aircraft until the battery is depleted. Only discharge the batteries in a fireproof location.
- Discharge the battery to 40%-60% if it will not be used for 10 days or more, as it can greatly extend the battery life.
- Fully charge and discharge the battery at least once every 3 months to maintain battery health.