You can edit a trigger definition. You need Database Manager permissions or higher to edit triggers.
To edit a trigger:
From Enterprise View or a custom view, select a database.
Right-click and select Edit, then Triggers.
In the Database Triggers window, select a trigger, and click Edit.
In the Edit Trigger dialog box, edit fields.
Click OK.
The trigger is updated.
“Monitoring Data Changes Using Triggers” in the Oracle Essbase Database Administrator's Guide
create trigger (MaxL) in the Oracle Essbase Technical Reference