Once the computer prompts you to initialize the drive just click initialize and Erase it right away.
If you do not see the drive when you click Initialize then if you are in the newest MAC OS High Sierra you can try these options:
- Click the view icon on the left and change it to All Devices. You should see the drive then and you can select it and Erase.
- Restarting the computer can cause it to show up in Disk Utility as well.
- Unplug and re-plug the drive in.
