Syntax:
DROP {PROCEDURE | FUNCTION} [IF EXISTS] sp_name

This statement is used to drop a stored procedure or function. That is,
the specified routine is removed from the server. You must have the
ALTER ROUTINE privilege for the routine. (That privilege is granted
automatically to the routine creator.)

The IF EXISTS clause is a MySQL extension. It prevents an error from
occurring if the procedure or function does not exist. A warning is
produced that can be viewed with SHOW WARNINGS.

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

