It's very simple, all you need is your reservation number indicated in your confirmation email and to click here: https://mamashelter.hotelandbook.com/en/cancellation/search-booking.shtml.
FLEXIBLE RATES
Standard reservations at Flexible Rates may be cancelled or amended 48 hours before 12:00pm local time on the due date of your arrival.
BEST AVAILABLE RATES, PACKAGES AND RACK RATES
Saver Rates (best available rates, rack rates, special offers and promotions) may not be cancelled or amended.