Unregisters the frame for an event. Once unregistered, the frame's OnEvent script handler will not be called for that event.
Unregistering from notifications for an event can be useful for improving addon performance at times when it's not necessary to process the event. For example, a frame which monitors target health does not need to receive the UNIT_HEALTH event while the player has no target. An addon that sorts the contents of the player's bags can register for the BAG_UPDATE event to keep track of when items are picked up, but unregister from the event while it performs its sorting.
