I think the answer depends on your needs. Do you want to loose the data that is on the tape ? Do you want to keep the data that is on tape ?
If you dont care to keep the data then you need to do nothing as the images written to that tape will expire and you can re-use the tape for some other backup.
If you want to keep the data then you can freeze the tape (which I am not 100% sure about) or you can manually change the expiry date to some date later in the future (i.e. 01/01/2050)
Hope this helps.