You can only change the delivery date of your shipment, in case it is undelivered (NDR status) due to some reason.
You can select the delivery date within 7 days since your order was marked undelivered and it can be done at the NDR Panel and the customizable tracking page.
To change the delivery date of your undelivered order from the NDR Panel-
- Go to Rate Calculator--> NDR
- Click on the Re-attempt button