How to Change Partial delivery indicator on delivery document

Hello All,

I have created a sales order with Partial delivery indicator as "C". Created delivery for the full quantity and saved.

Now i want to change the quantity on delivery line item and system is not allowing me. Parital delivery indicator on the delivery line item is disabled.

Scenario: Distribution has requested customer service to talk to the customer for partial delivery . Customer agreed for partial delivery and Customer service has removed parital delivery indicator "C' from the sales order.

Distribution still cannot process the delivery by changing the quantity.

Is there anyway i can change the partial delivery indicator on the delivery line item.

Thank you for you help in advance,

-Naga Shakelli