"If I go to Devices\devicename\Slots, the Format option is available but I am not seeing the tapes that I need to format"
If this is the case, are you sure that the tape is in the library?. You may want to do a Barcode scan (if available) to update the IDB as to what tapes are in the library
Your screen shot did not provide enough detail to make further assessments. In the Media Pool, right-click on this media, and pick Properties. if it is in the library, you will see it in the 'Location' line, for example, looking something like
[Tape Library: 21]
which would mean that it is in the logical library named "Tape Library" in slot 21