Step 1: Go to Inventory---Sales Bill
Step 2: Select the customer, select the rep and enter the items.
Step 3: Once you finish entering the items press "Ctrl+T" to convert the bill to DC.
Step 4: A pop up will appear as in the picture , select "No" to convert to DC.
Step 5: If you go to Inventory---Delivery Challan and choose to see previous challan, you can the the converted sales bill be saved as DC.