How to erase and reformat using Windows

1. Press the Windows Symbol + R on your keyboard to open the Run box.
2. Type diskpart, and press Enter. A command window will open.
3. Type list disk and press Enter.
4. Choose the drive by entering select disk x; for example "select disk 2" if it is listed as disk 2 (make sure to select the correct drive!). Press Enter.
5. Type clean and press Enter.
6. The drive's formatting will be removed. It will say "Successful" upon completion.
7. Type convert gpt and press Enter.
8. Type create part pri and press Enter.
9. Type format fs=ntfs quick and press Enter.*
10. Type assign and press Enter. It will say "Successful" upon completion.

Note: Select exFAT if you will be using the drive with both Windows & Mac.

How to format a drive using Mac OS

1. Connect the drive to your computer.
2. Open Disk Utility. (Applications > Utilities > Disk Utility). Click View > Show All Devices.
3. From the list on the left, click on the external drive (not the indented item underneath).
4. Click the 'Erase' tab at the top of the Disk Utility window.
5. Enter a name for the drive and select 'Mac OS Extended (Journaled)' or 'APFS' from the Format drop down menu.*
6. Select 'GUID' from the Scheme drop down menu.
7. Click the 'Erase' button. You will be presented with an 'Are you Sure' dialog. Confirm to complete the action.

Note: Select exFAT if you will be using the drive with both Windows & Mac.