delete <yourtable>
where exists(select * from <yourtable> a
where <yourtable>.<pk1> = a.<pk1>
and <yourtable>.<pk2> = a.<pk2>
...
and <yourtable>.<pkn> = a.<pkn> )
where exists(select * from <yourtable> a
where <yourtable>.<pk1> = a.<pk1>
and <yourtable>.<pk2> = a.<pk2>
...
and <yourtable>.<pkn> = a.<pkn> )
delete table1 where rowid=(select min(rowid) from table1 b where ...)