How do I remove a subscription autopay from my Apple Pay before the next billing cycle?

Your Netflix account is only managed on their website. Check with them to make sure you are not going to receive any further charges, which should be the case if you have cancelled the service on their website already. Netflix does not allow Apple to manage your subscription, so you will have to deal with Netflix for cancellation, refunds, or any other issue with them charging you. ApplePay only facilitates the transfer of your financial info securely without providing them your actual card number. ApplePay does not approve or deny your transactions, that is done by the payment method used. Any dispute from a charge still needs to be made with the Credit/Debit card, if you are unable to resolve the issue with Netflix.

If you cancelled your subscription you would not be charged. You can check if the subscription is really cancelled via settings>your name> subscriptions