You only need an endpoint, with external_ref, to delete/cancel an order. No body text is required. An order can only be deleted before it's been planned.
If you need to cancel or remove an order from its route, this needs to be updated manually in our Last Mile Platform. Contact our support if you don't have access to update this yourself.
DELETE /api/orders/<EXTERNAL_REF>
(Empty)
Responses
{
"status" : "OK",
"external_ref" : "A1"
}