How to Hide the "Gutenslider" Admin Menu

function plt_hide_gutenslider_menus() {
	//Hide the "Settings → Gutenslider" menu.
	remove_submenu_page('options-general.php', 'settings-page-gutenslider');
}

add_action('admin_menu', 'plt_hide_gutenslider_menus', 1000000000);

Where do I put this code?