Hi,
I’ve had the same problem at my site LaptopHQ, and only after studying wp-includes/default-filters.php I was able to fix it. It turns out that you need to remove the action with the same parameters it was added. In your case, try this:
remove_action('wp_head', 'feed_links_extra', 3); // Remove category feeds
remove_action('wp_head', 'feed_links', 2); // Remove Post and Comment Feeds
