I can’t think of too many reasons why you’d want to disable all of your RSS feeds, but the one that I came across recently was for a client of mine who asked me to create a WordPress site that was only accessible to paid members. In conjunction with the Amember software, I created a viable site for him, but in order to truly hide all of the content from freeloading eyes, I needed to disable the RSS feeds to avoid the content being accessed that way.
As usual, with WordPress being as versatile as it is, it didn’t take much to put together a function to disable all of the RSS feeds on the site. This includes all the different versions of the feed, like the RDF feed and the Atom feed. So all you need to do is drop this into your functionality plugin (or functions.php if you haven’t joined the revolution yet):