Existing traffic on the Traffic Instructions window, along with the traffic record ID, can be purged from the system by clicking the Delete 
button on the tool bar.
Unlike Erase, which only clears the work space, Delete destroys the full record as well as any reference to previous traffic for the selected media. It is the equivalent of the traffic having never been created. Use this feature with extreme caution. If traffic has been previously issued to media, this button is disabled.