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 nonexistent events instead using IF
EXISTS.

Beginning with MySQL 5.1.12, this statement requires 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

