How to Hide Open Directory Admin Menus

function plt_hide_open_directory_menus() {
	//Hide the "Open Directory" menu.
	remove_menu_page('OPENDIRECTORY_page');
	//Hide the "Open Directory → Open Directory" menu.
	remove_submenu_page('OPENDIRECTORY_page', 'OPENDIRECTORY_page');
	//Hide the "Open Directory → Customize Directory" menu.
	remove_submenu_page('OPENDIRECTORY_page', 'OPENDIRECTORY_menu');
}

add_action('admin_menu', 'plt_hide_open_directory_menus', 11);

Where do I put this code?