How to Hide Travelpayouts Admin Menus

function plt_hide_travelpayouts_menus() {
	//Hide the "Settings → Travelpayouts" menu.
	remove_submenu_page('options-general.php', 'travelpayouts_landing_page');
	//Hide the "Travelpayouts" menu.
	remove_menu_page('travelpayouts_options');
}

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

Where do I put this code?