function tncpvfw_support_disable_pdfviewer_archive_and_hide_from_google($args, $post_type) {
    if ($post_type === 'pdfviewer') {
        $args['has_archive'] = false;
    }
    return $args;
}
add_filter('register_post_type_args', 'tncpvfw_support_disable_pdfviewer_archive_and_hide_from_google', 10, 2);

function tncpvfw_support_add_noindex_meta_tag() {
    echo '<meta name="robots" content="noindex, nofollow" />';
}
add_action('tnc_pvfw_head', 'tncpvfw_support_add_noindex_meta_tag');