Code to Disable “Tag Archives” in WordPress

/* Disable Tag Archives WordPress, Redirects to 404 */
add_action('template_redirect', 'wpflt_remove_wp_tag_archives');
function wpflt_remove_wp_tag_archives(){
  if( is_tag() ) {
    global $wp_query;
    $wp_query->set_404();
  }
}

WordPress Tag Archive URL: https://example.com/tag/tag-name/

If you are not using any Tags, or using WordPress for Single Page site or as an Ecommerce Website, you should disable Tag Archives. Above code redirects Tag Archives to 404 Page.

Below code to functions.php redirects WordPress Tag Archive URL to Homepage.

/* Disable Tag Archives WordPress, Redirects to Homepage */
add_action('template_redirect', 'wpflt_remove_wp_tag_archives');
function wpflt_remove_wp_tag_archives(){
  if( is_tag() ) {
        $target = get_option('siteurl');
        $status = '301';
        wp_redirect($target, 301);
        die();
  }
}