An advanced purchase rate is prepaid so they charge your card upfront. Within a few days, the charge should post into your credit card or bank account. Changing or cancelling your reservation online doesn't change that. You already got charged.

Your only glimmer of hope is to call the hotel yourself and ask them to cancel it without charging you or to refund it, the sooner the better. Sometimes, they will let you change the reservation to another date. It might help if you come up with a sad story or valid reason for the cancellation. Individual hotels/properties have complete control over their charges and reservations but usually, they will be unwilling to cancel/refund such prepaid rates for you. They could but they don't have to and you shouldn't expect them to. As per the rate's policy, it's non-refundable.