Unplug the drill or remove the battery
Set the drill to reverse if needed
Open the chuck fully
Hold the chuck firmly
Turn the chuck counterclockwise by hand
Use the chuck key if your drill has one
Loosen the jaws until the bit releases
Pull the drill bit straight out
If the bit is stuck, apply penetrating oil to the chuck
Tap the chuck lightly while loosening it
Use pliers on the chuck if necessary
If the chuck is damaged, replace it