Korg Electronic Keyboard Parameter Manual page 736

Disk mode
When you execute Quick Erase, the files and data
will appear to be gone, but the data itself will
remain on the disc until it is overwritten. If you
want to erase data that should not be seen by
someone else, execute Full Erase to erase the data
completely.
4. Press the OK button to execute the Erase
operation, or press the Cancel button to cancel
without executing.
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