How Are Automatic Payments Cancelled?
There are two ways to cancel an automatic payment:
• The system will cancel an automatic payment behind-the-scenes if the related bill (if any) is reopened BEFORE the automatic payment is interfaced to the financial institution. When you recomplete the bill, the system will create a new automatic payment that reflects the new amount due (and the canceled automatic payment will net out the original automatic payment).
• An operator can cancel an automatic payment (refer to How To Cancel A Tender) at any time. You would do this if the automatic payment was rejected by the financial institution.
Fastpath: 
Refer to Credit / Correction Notes and Auto Pay for information about how a credit note may cancel an automatic payment.