To cancel or manage a reservation go to https://hotels.smartertravel.com/n/hotels/reservations and enter your SmarterTravel confirmation number and email. Before canceling your booking, it's a good idea to see if you booked a refundable room. If not, you might have a penalty fee. When you booked the hotel, the policy would have been displayed when you chose the room, upon checkout, and it's also in the confirmation email under "Important Information." In addition, the refund policy is available when you log in to manage your reservation.
You can also find the cancelation policy at the bottom of your confirmation email.