This drill is really simple and very effective at teaching you how to release the club.
First, setup to a ball as normal but take your right foot and place this foot well back from your left foot so
you are forming a very closed stance.
If you are not sure whether your feet are closed enough it's better to over exaggerate, rather than the opposite.
From this very closed stance position you simply have to swing as normal, with one exception. When swinging try to keep your right foot on the ground during the entire swing.
Doing this means that you are forced to use your arms and hands to release the clubhead, and that's why this drill is so good. Keep doing this drill until you release your hands automatically from a square stance position.
One parting word of warning: Learning to release the hands properly will result in a great deal more distance!!