If a lookup list value is not used in your business processes, and you do not need this value in the database, you can permanently delete it.
To delete items from a drop-down list:
Customization >[Module] > [Object Class] > Classification section, go to the section for the drop-down list whose items to delete.
Select one or several items that you want to delete.
NOTE: Certain values are marked as system (i.e. the “Closed” value for Ticket Status). Alloy Navigator Express relies on these values, so they cannot be deleted.