How to Hide Smart Forms Admin Menus

function plt_hide_smart_forms_menus() {
	//Hide "Smart Forms".
	remove_menu_page('smart_forms_menu');
	//Hide "Smart Forms → Smart Forms".
	remove_submenu_page('smart_forms_menu', 'smart_forms_menu');
	//Hide "Smart Forms → Entries".
	remove_submenu_page('smart_forms_menu', 'smart-forms/smartforms.phpentries');
	//Hide "Smart Forms → Support/Wish List".
	remove_submenu_page('smart_forms_menu', 'smart-forms/smartforms.phpwish_list');
	//Hide "Smart Forms → Settings".
	remove_submenu_page('smart_forms_menu', 'smart-forms/smartforms.phpsettings');
}

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

Where do I put this code?