How to delete duplicate record

How do I delete a duplicated records?
Here I've 7 duplicated records and tried to delete 6 from them.

I tried this query but has error
b2b=> delete from biztypes where bizid = (select bizid from biztypes
where bizid = 'B116' limit 6);
ERROR: More than one tuple returned by a subselect used as an
expression.

I tried this query, but all records are deleted.
b2b=> delete from biztypes where bizid = (select bizid from biztypes
where bizid = 'B116' limit 1);
DELETE 7

Any help are very much appreciated..
Thanks. Wahab