Discarding tapes

There are destruction companies that specialize in destroying tapes (and often also paper and whatever else that could contain confidential data).

If you have a company that takes care of destroying your old paperwork with confidential information, contact them to see if they can also take care of your tapes.

If you are interested in removing data from a small amount of tapes you can run a "long erase" or "secure erase". This will completely overwrite the data on the tape. These operations take as long to run as it would take for the drive to completely write a full tape, so it is not a very efficient method if you have a large amount of tapes.

For larger amounts as stated earlier you will need to contact a company that specializes in that field.