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Connect your SD card to your computer using an adapter.
In macOS X Finder, go to Utilities (Go > Utilities or ⇧⌘U) and open Disk Utility.
Choose the SD card entry from the left.
Select Erase from the top of the window (see Image 2).
Choose ExFAT - if using OS/firmware lower than 6.2.94 or using a Series 2 or older player, choose MS-DOS (FAT).
Click the Erase button.
Once the process has finished, click the eject icon next to the SD card on the left to unmount. It is now safe to remove the SD card from the computer.
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