How exactly can I de-select Prerequisite Categories or Events? The cursor seems to select one or rest on one of them by default. There's not a 'None' choice. How do I blank out or de-select those fields in the Event page (Event Management)?
A prerequisite event or category would never be selected automatically. You would have to have clicked them. If accidental, you can de-select using CTRL-Click (or Command-Click on a MAC).