DROP FUNCTION
Drops a user-defined function. Only the owner of a UDF may drop it (there is no separate DROP FUNCTION
privilege).
DROP FUNCTION [ IF EXISTS ] <function_name>
Parameters
[ IF EXISTS ] String Optional
If specified, prevents an exception when the function does not exist.
<function_name> String
The name of an existing user-defined function.
Examples
Create a functionCREATE FUNCTION hello() RETURNS VARCHAR RETURN 'Hello World!';
DROP FUNCTION hello;
DROP FUNCTION IF EXISTS hello;