Untested, of course... 😉
DELETE dbo.abn_extract
FROM dbo.abn_extract E
INNER JOIN dbo.ABN_File_Header H
ON SUBSTRING(E.[Column 0], 1, 13) = H.Header_Id
SQL Server is one of the few RDBMS's that have a FROM clause (2 actually) available... everyone else has to use correlated sub-queries. Lookup DELETE in Books Online for a better understanding of the statement.
--Jeff Moden
Change is inevitable... Change for the better is not.