If you download our much more detailed manual here:- http://www.ajamsonic.com/KETRON%20SD9%20Pro%20MANUAL%20-%20ENGLISH%20FINAL.pdf
... Go to Page 184 (DISK EDITOR) which explains how to copy, move, delete ...etc from one media device to another.
In a nutshell:-
* Insert your USB key
* Press MEDIA
* Touch the SD9's SSD (so the SD9 knows this will be the source disk).
* Touch DISK EDIT to display the different disk edit controls (COPY, MOVE, DELETE .... etc)
* Go to the folder where your recording is and touch it (highlighted in grey).
* Touch COPY on the bottom of the screen.
* Select the DESTINATION (your USB key)
* Then touch PASTE and the selected file(s) will be copied over.
** Same operation for DELETE, MOVE ... etc.
Hope this helps.