Удаляем стандартные META-теги Drupal 8

<meta charset="utf-8" />
<meta name="Generator" content="Drupal 8 (https://www.drupal.org)" />
<meta name="MobileOptimized" content="width" />
<meta name="HandheldFriendly" content="true" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />

function THEME_page_attachments_alter(array &$page) {
  $meta = [
    'system_meta_generator',
    'MobileOptimized',
    'HandheldFriendly',
  ];
 
  foreach ($page['#attached']['html_head'] as $key => $value) {
    if (in_array($value[1], $meta)) unset($page['#attached']['html_head'][$key]);
  }
}