How to Hide Bookingflix Admin Menus

function plt_hide_terminflix_menus() {
	//Hide "Bookingflix".
	remove_menu_page('terminflix');
	//Hide "Bookingflix → Bookingflix".
	remove_submenu_page('terminflix', 'terminflix');
	//Hide "Bookingflix → Create first Calendar".
	remove_submenu_page('terminflix', 'quickstart_terminflix');
	//Hide "Bookingflix → Connect to Wordpress".
	remove_submenu_page('terminflix', 'signin_terminflix');
	//Hide "Bookingflix → Imprint".
	remove_submenu_page('terminflix', 'imprint_terminflix');
}

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

Where do I put this code?