template.php

<?php
/**
 * Override or insert variables into the HTML head.
 *
 * @param $head_elements
 *   An array of variables to pass to the HTML head.
 */
function MYTHEME_html_head_alter(&$head_elements) {
  // remove unneeded metatags
  $remove = array(
    //'system_meta_content_type', // Content Type
    'system_meta_generator',      // Generator
    'metatag_canonical',          // Canonical Link
    'rdf_node_title',             // DC:Title
  );
  foreach ($remove as $item) {
    if (isset($head_elements[$item])) {
      unset($head_elements[$item]);
    }
  }

  // remove unneeded links
  $remove = array(
    '/^drupal_add_html_head_link:shortcut icon:/', // Favicon
    '/^drupal_add_html_head_link:shortlink:/',     // Shortlink
  );
  foreach ($remove as $item) {
    foreach (preg_grep($item, array_keys($head_elements)) as $key) {
      unset($head_elements[$key]);
    }
  }
}