Windows
1. Plug in the USB drive.
2. Open File Explorer and right-click the USB drive.
3. Select Format.
4. Under "File system", select FAT32.
5. Check Quick Format.
6. Click Start.
Mac
7. Plug in the USB drive.
8. Open Disk Utility (search in Spotlight).
9. Select the USB drive from the left panel.
10. Click Erase.
11. Set the format to MS-DOS (FAT) — this is FAT32.
12. Click Erase to confirm.