system_module_test.module

<?php

/**
 * @file
 * Provides System module hook implementations for testing purposes.
 */

/**
 * Implements hook_page_attachments_alter().
 */
function system_module_test_page_attachments_alter(&$page) {

  // Remove the HTML5 mobile meta-tags.
  $meta_tags_to_remove = [
    'MobileOptimized',
    'HandheldFriendly',
    'viewport',
    'ClearType',
  ];
  foreach ($page['#attached']['html_head'] as $index => $parts) {
    if (in_array($parts[1], $meta_tags_to_remove)) {
      unset($page['#attached']['html_head'][$index]);
    }
  }
}