Drupal HEAD remove shortlink and generator

function themename_html_head_alter(&$head_elements) {
  foreach ($head_elements as $key => $element) {
    if (isset($element['#attributes']['rel']) && $element['#attributes']['rel'] == 'shortlink') {
      unset($head_elements[$key]);
    }
    if (isset($element['#attributes']['rel']) && $element['#attributes']['rel'] == 'alternate') {
      unset($head_elements[$key]);
    }
  }
  unset($head_elements['system_meta_generator']);
  $head_elements['system_meta_content_type']['#attributes'] = array(
    'charset' => 'utf-8'
  );
}