You can modify and drop a trigger by using Procedural Language (PL).
Modify a trigger
To modify a trigger, you can use only the REPLACE TRIGGER statement. This statement is a DDL statement.
Generally, you can use the following syntax to create or modify a trigger:
CREATE OR REPLACE TRIGGER trigger_name ...
If the value of trigger_name does not exist, the trigger is created. If the value of trigger_name exists, the trigger is modified.
Drop a trigger
You can use the DROP TRIGGER statement to drop a trigger. The syntax is as follows:
DROP TRIGGER trigger_name;
When you drop a table, the triggers created on the table are also dropped.