There are a few reasons you'd want to edit your tickets:
1. Did you request too many tickets? That's easy! Simply edit your request in your 1iota account, and reduce the number of tickets. You have up until the day before an event to do this.
REMEMBER! You cannot undo this action. Once you've deleted a ticket, it's gone. That is why we ask you to confirm the deletion.
2. Did you want to request more tickets than the site allows? You'll need to have another member of your party submit a request with their own 1iota account. Tickets cannot be increased in number. You also cannot write in the ticket comment that you want more tickets than allowed.
3. If you accidentally requested less tickets than you wanted, you'll need to delete your request and resubmit it, or have another member of your party submit a ticket request. Tickets and ticket requests cannot be increased in number once they've been submitted.
This FAQ has more information.