MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
DROP TRIGGER [IF EXISTS] [schema_name.]trigger_name This statement drops a trigger. The schema (database) name is optional. If the schema is omitted, the trigger is dropped from the default schema. DROP TRIGGER requires the TRIGGER privilege for the table associated with the trigger.
Use IF EXISTS to prevent an error from occurring for a trigger that does not exist. A NOTE is generated for a nonexistent trigger when using IF EXISTS. See Section 15.7.7.42, “SHOW WARNINGS Statement”.
Triggers for a table are also dropped if you drop the table.