Disable WordPress RSS-Feed via functions.php

Drop this code snippet in the functions.php file to completely disable RSS feed on your site.

/**
 * disable feed
 */
function fb_disable_feed() {
	wp_die( __('No feed available, please visit <a href="'. get_bloginfo('url') .'">Home</a>!') );
}

add_action('do_feed', 'fb_disable_feed', 1);
add_action('do_feed_rdf', 'fb_disable_feed', 1);
add_action('do_feed_rss', 'fb_disable_feed', 1);
add_action('do_feed_rss2', 'fb_disable_feed', 1);
add_action('do_feed_atom', 'fb_disable_feed', 1);

Source