The trigger must be in your own schema or you must have the
TRIGGER system privilege. To drop a trigger on
DATABASE in another user's schema, you must also have the
TRIGGER system privilege.
Specify the schema containing the trigger. If you omit
schema, then Oracle Database assumes the trigger is in your own schema.
Specify the name of the trigger to be dropped. Oracle Database removes it from the database and does not fire it again.
DROP TRIGGER hr.salary_check;