DELETE t FROM
(
SELECT (SELECT COUNT(*) + 1 FROM Table WHERE code=t.code AND ID > t.ID) AS RowNo,
code,
Col2,
Col3,
Col4
FROM Table t
)t
WHERE t.RowNo<>1

For SQL 2005:

DELETE t FROM
(
SELECT ROW_NUMBER() OVER(PARTITION BY code ORDER BY ID DESC) AS RowNo
FROM Table
)t
WHERE t.RowNo<>1

DELETE		x
FROM		table1 AS x
LEFT JOIN	(
			SELECT		MAX(ID) AS ID
			FROM		table1 
                ) AS y ON y.ID = x.ID
WHERE		y.ID IS NULL