DELETE FROM ITEM
WHERE
  (
    ITEM_CODE NOT IN (
      SELECT
        ITEM_CODE
      FROM
        STOCK
    )
    OR ITEM_CODE IN (
      SELECT
        ITEM_CODE
      FROM
        STOCK
      GROUP BY
        ITEM_CODE
      HAVING
        MAX(COALESCE(LAST_DELIVERY_DATE, '2099-12-31')) <= DATE ('2023-06-01', '-6 months')
        AND SUM(ACTUAL_AMT) = 0
    )
  )
  AND STOCK_MANAGEMENT_TYPE = 1;