Disallow tags in WordPress

I don’t use tags in WordPress, how can I disable this functionality?

Add this code to your plugin:

<?php
// Remove submenu
add_action('admin_menu', 'wpster_remove_sub_menus');
function wpster_remove_sub_menus() {
remove_submenu_page('edit.php', 'edit-tags.php?taxonomy=post_tag');
}
// Remove tags from page and post
add_action('init', 'wpster_remove_tags');
function wpster_remove_tags(){
register_taxonomy('post_tag', array());
}
?>