@vijay I had that same scenario while back but it was with the PO not SO. I bypassed it in a bit unorthodox way, I created sets of item (non inventory for purchase in my case) and named it same as the GL account or in some case as cost category. You can try this method, otherwise item is a mandatory field for almost all transaction, note that item is the object what drives the transaction. In other word you cannot have a running car without an engine. My 2 cents worth