function plt_hide_docs_menus() {
//Hide the "Docs" menu.
remove_menu_page('edit.php?post_type=doc');
//Hide the "Docs → All Docs" menu.
remove_submenu_page('edit.php?post_type=doc', 'edit.php?post_type=doc');
//Hide the "Docs → Add New Doc" menu.
remove_submenu_page('edit.php?post_type=doc', 'post-new.php?post_type=doc');
}
add_action('admin_menu', 'plt_hide_docs_menus', 15);