You could try this: - Use Nikon Transfer (I am using version 1.1.1) - go to the 'Preferences' tab - check the 'Delete Original Files After Transfer'.
I don't use the feature myself (yet); it may work for you.
Please use it with caution though. Just think, if after you download, there is a problem and somehow it doesen't get to where you want it, and you have it checked off as deleting, there is the potential of loosing your images completely.
"The Nikon did the work; I just happened to be behind it at the time." TP