Delete from table where not in another table using two columns
I suspect you're after something like this:

DELETE FROM tbl1
FROM tbl1
    LEFT OUTER JOIN tbl2
        ON tbl1.PK1 = tbl2.PK1
        AND tbl1.PK2 = tbl2.PK2
        AND tbl2.DateStr &gt;= GETDATE() - 365
WHERE tbl2.PK1 IS NULL
    AND tbl2.PK2 IS NULL


Yes, you have two FROM clauses with a multi-table DELETE statement. This is essentially just an anti-join turned into a deletion.