Trying to delete a shipping advice but the system throws an error message? 

If you get an error message that states 'Picking is already started' when trying to delete a shipping advice that is in status 1, you can try to add the shipping advice to the picking queue again to 'undo picking'. 

1. Add the shipping advice (CSA) to picking queue, under "Activities and operations", that will forward the
    document to status 2. 

2. Choose the option: "Start picking" under "Activities and operations", that should forward the document to 
    status 3. 

3. When this is done, you have the option: "Pick shipping advice", in the same context menu. 
    Choose this and you will enter the PICK application.

Once in this application, choose the option: "Undo pick all" :

4. Return to the shipping advice (CSA) (by using the escape button) and you should now have the option to:
    "Backward shipping advice from picking/shipping queue".

This will set the document back in status 1 and you will be able to choose: "Delete all items", under the context menu: "Open / Discard shipping advice". 

If that works fine, use the option: "Discard shipping advice", under the same context menu.

This will re-open the sales order (COA) to status 8 that the shipping advice (CSA) was based on 

and you can continue to either ship it out again, edit or cancel the order.