I don't know if this has been covered before but if so I can't find the thread.
I am trying to do a bit of housekeeping on some of the files I have uploaded (chiefly removing old versions which have been superceded) by deactivating them in the user/files section. For some reason, no doubt my own stupidity, it only seems to work intermittently for me. Frequently when I return to the page, files I have definitely "deactivated" reappear is if I hadn't done anything. Other times it works.
The deactivated files should now return a 404 when being accessed.
You can deactivate any of your files if you are logged in with the account that created them. Go to the file and click the red deactivate link to deactivate. The next time you or anyone tries to visit the file you should get a 404 message. You can get a list of your active files here: http://my.creativecow.net/Simon-Ubsdell/files