function plt_hide_wp_hidden_password_protected_page_menus() {
//Hide the "Settings → WP Hidden Password Protected Pages Settings" menu.
remove_submenu_page('options-general.php', 'wp-hidden-password-protected-page/wp-hidden-password-protected-pages.php');
}
add_action('admin_menu', 'plt_hide_wp_hidden_password_protected_page_menus', 11);