DELETE FROM ITEM
WHERE ITEM_CODE NOT IN (SELECT ITEM_CODE FROM STOCK) 
    OR ITEM_CODE IN (SELECT ITEM_CODE 
                    FROM (SELECT ITEM_CODE, MAX(LAST_DELIVERY_DATE) MAXDATE, ACTUAL_AMT
                        FROM STOCK 
                        GROUP BY ITEM_CODE, ACTUAL_AMT)
                    WHERE MAXDATE <= DATE('2023-06-01', '-6 months') 
                            AND ACTUAL_AMT = 0)