According to the SnapTravel support article, you can check your refund policy on your Snaptravel confirmation page which was sent to your email. You can also access the confirmation page online by typing 'my bookings' in your Snaptravel messaging thread.
If your booking is refundable, you can cancel it following the steps provided at snaptravel.freshdesk.com/support/solutions/articles/480********-how-do-i-cancel-a-booking-.
If your booking is non-refundable, you should submit a cancellation request at snaptravel.com/submit_ticket.