Sometimes when you try to remove an invoice from TOE system it raise an error message;

Failed to remove the requested invoice.

Invoice 'XXXXXXXX' cannot be removed due to the fact it has closed pallets/cartons on it. Please either reject the invoice, or reopen all the cartons/pallets from the shipment screen.

Please check the logs for more details.

This means the the cartons/pallets are locked. This normally happens when the invoices are on ReadyToUpload stage or when the labels are printed. 
If you are going to remove the invoice you need to make sure that the closed pallet/carton labels are re-opened.

How to re-open carton/pallet labels;

  1. Select the invoice you need to remove, right click and select ShipmentInfo

2.Then select Reopen Cartons and Pallets

Click OK and Close.

3. Now go to Shipments/Invoices tab again, right click and select Remove