With the charger in the cream whipper, hold the cream whipper upside down over a sink or plate, push the nozzle to squeeze out any remaining whipped cream and gas. Keep holding the nozzle until the sound of the gas stops.
Rinse the equipment along with your empty cream charger canister with water to remove any leftover residue, so the canister is clean before you dispose of it.
Once completely empty of gas, your charger can be disposed of occurring to local disposal guidelines for gas chargers.