Bookings made within the last 24 hours, can usually be cancelled for free.
This is how it works
1. Go to "My Bookings".
2. Open the booking you want to void.
3. Click on "Cancel booking".
4. Cockpit will now try to verify if voiding is allowed and will void the ticket afterwards.
5. If voiding is not possible you will be asked to use the Refund Form.