The easiest way is to delete/rename the wp-feed.php. If you don’t want people who attempt to use it receive a 404 error, you can edit the wp-feed.php and comment everything out:
<?php
/*
if (empty($doing_rss)) {
$doing_rss = 1;
require('wp-blog-header.php');
}
// Remove the pad, if present.
$feed = preg_replace('/^_+/', '', $feed);
if ($feed == '' || $feed == 'feed') {
$feed = 'rss2';
}
if ( is_single() || ($withcomments == 1) ) {
require('wp-commentsrss2.php');
} else {
switch ($feed) {
case 'atom':
require('wp-atom.php');
break;
case 'rdf':
require('wp-rdf.php');
break;
case 'rss':
require('wp-rss.php');
break;
case 'rss2':
require('wp-rss2.php');
break;
}
}
*/
?>
