disk utility – How to reformat hdd only viewable under (About Mac) -> (System Report) -> (USB 3.0 Bus)?

After changing to a new external USB hdd for Time Machine my previous external USB drive used for Time Machine (almost) disappeared. My old drive is a Western Digital, My Passport 25E3 for Mac (1-tb). It is not recognized in:

  • Disk Utility
  • (About This Mac) –> (Storage)
  • **/Volumes$**ls -l

However, I can see the old Time Machine drive here: (About This Mac) –> (System Report) –> (USB) –> (USB 3.0 Bus) -> My Passport 25E3

What can I do to reformat that old Time Machine drive and mount it as just a normal external drive? I’ve rebooted several times and used different cables.