How to Hide the "TPV Configuration" Admin Menu

function plt_hide_pago_redsys_tpv_grafreak_menus() {
	//Hide the "Settings → TPV Configuration" menu.
	remove_submenu_page('options-general.php', 'pago-redsys-grafreak');
}

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

Where do I put this code?