Copy codefunction wp_maintenance_mode(){ 
  if(!current_user_can('edit_themes') || !is_user_logged_in()){ 
    wp_die('Maintenance.'); 
  } 
} 
add_action('get_header', 'wp_maintenance_mode'); 
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="https://excel-td.com/wp-sitemap-index.xsl" ?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"><sitemap><loc>https://excel-td.com/wp-sitemap-posts-post-1.xml</loc></sitemap><sitemap><loc>https://excel-td.com/wp-sitemap-posts-page-1.xml</loc></sitemap><sitemap><loc>https://excel-td.com/wp-sitemap-taxonomies-category-1.xml</loc></sitemap><sitemap><loc>https://excel-td.com/wp-sitemap-users-1.xml</loc></sitemap></sitemapindex>