[otrs] Deselect

I have a quick question. When creating or modifying Notification Events, there are times a select is made and may need to be cleared. Say for instance, I click "Article Create" and then decide I don't want anything in that category. How does one remove any selections? I only see where you can select another option in that category, but no clear selection option. Does this exist anywhere, or am I missing a keystroke? Thanks, ~Tim