Rejecting a sales order in sap byd

A sales order was fully processed and invoiced but contained an error in the sales values. Everything following the sales order has been reversed or cancelled - customer demand, outbound delivery, invoice, etc. and the sales order is in process.

How can I reject the sales order? (It has been replaced with a new one)

The pricing tab will not allow me to update any pricing/ manual pricing and the reject option will not process.