How to Hide the "diggZ-Et" Admin Menu

function plt_hide_diggz_et_menus() {
	//Hide the "Settings → diggZ-Et" menu.
	remove_submenu_page('options-general.php', 'diggZ-Et.php');
}

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

Where do I put this code?