Choose the Unreserve... menu item to cancel one or more
  reservations of a generation of an element.

  You cannot unreserve a generation held by another user
  unless you hold BYPASS privilege or unless you are
  granted BYPASS access to the element by an access
  control list (ACL).

  If you have more than one reservation of an element or if
  you are canceling another user's reservation, you must
  specify the exact reservation to be canceled.  You do
  this by using either the Generation option or the
  Reservation Identification button in the Options dialog
  box (choose the Options button).