Syntax:
DROP EVENT [IF EXISTS] event_name

This statement drops the event named event_name. The event immediately
ceases being active, and is deleted completely from the server.

If the event does not exist, the error ERROR 1517 (HY000): Unknown
event 'event_name' results. You can override this and cause the
statement to generate a warning for non-existent events instead using
IF EXISTS.

Beginning with MySQL 5.1.12, this statement requires the having the
EVENT privilege for the schema to which the event to be dropped
belongs. (In MySQL 5.1.11 and earlier, an event could be dropped only
by its definer, or by a user having the SUPER privilege.)

URL: http://dev.mysql.com/doc/refman/5.1/en/drop-event.html

