Use the Cancel Bill Payment endpoint to cancel a bill-payment transaction. Only transactions in status N (ready to process), W (waiting to be printed), or P (check printed) can be canceled: all other statuses return status code 435-02.
Keep in mind that you cannot cancel a bill payment that has already been processed. When you create an electronic bill payment with a process date of "now," the payment is processed within five minutes. If the payment is scheduled for a future date, you can still cancel it (paper or electronic), as long as it has not been processed yet.
When canceling a paper bill payment in status P, it is possible that the check will not be canceled because of processes that are downstream from making the cancelation request with this endpoint.