DROP FUNCTION function-name
Identifies the particular function to be dropped, and is valid only if there is exactly one function instance with the function-name in the schema. The identified function can have any number of parameters defined for it. If no function with the indicated name in the named or implied schema, an error (SQLSTATE 42704) will occur. An error will also occur if there is more than one specific instance of the function in the named or implied schema.