Just like any other document: drag it onto the Trash icon on the Dock (OS X)
or on the Desktop (OS 9), and empty the trash.
If you mean from the "File" menu in Word, press Command + Option + - (the
key between ")0" and "+="), and then select the document you want delete
from the File menu. It will then be removed.
To turn off the Recently Used File List, go to Word -> Preferences, choose
"General", and then uncheck the "Recently Used File List: __ entries"
option. Click OK to save.
