If you mean the recent files list (which you see when you click the Office
button), the deleted file will eventually be cycled off as new files are
opened (unless you click the pushpin, which will keep the file in the list).
There's an easy way to remove individual files from the recent list in
previous versions of Word, but not in Word 2007. If you really need to get
that file off the list NOW, rather than waiting, then set the number of
recent documents to 0, and then back to where you want it. Note, however,
that this will clear other files off the list, as well. (The setting is
here: Office button, Word Options, Advanced tab - Display subsection.)