If you do not wish to leave feedback for a member that you've interacted with then simply delete the booking to which the feedback request pertains. Do this via the Combined View or individual booking pages within the Emails & Bookings part of the site.
It is not possible to delete a DirectCam or DirectChat booking, so we have now added a new "Dismiss" checkbox next to the bookings that appear on your Leave Feedback page. Simply tick this box and then hit Update. Any rating information you've entered will be saved and any Dismiss boxes you've ticked will result in the session no longer appearing on that page.