Clears the contents of bookkeeping. When clearing, use the
service button to bring the arrow (>) to "YES (CLEAR)"
and press the test button. When data has been cleared, "COMPLETED"
will be displayed.
Bring the arrow to "NO (CANCEL)" and press the test
button to return to the menu mode without clearing the data.
Also, note that the game setting contents are not affected by
the backup data clear operation.