How to get rid of dups...

I need to get rid of all rows that have dups in the columns
tpa,pun,grn,claim ... i.e.

1--- 001 001 001 00-000001 John Doe
2--- 001 001 001 00-000001 Jane Doe
3--- 001 002 001 00-000001 John Doe

1 and 2 would be dups, 1 and 3 are diff records, 2 and 3 are diff
records.

I tried this as a test:

select count(claimid), tpa, pun, grn, claim FROM claim_import GROUP BY
tpa, pun, grn, claim HAVING count(claimid) > 1;
26 rows returned.

then

select distinct on (tpa,pun,grn,claim) count(claimid), tpa, pun, grn,
claim FROM claim_import GROUP BY tpa, pun, grn, claim HAVING
count(claimid) > 1;

and still had 26 rows returned. not sure how that can happen.

Anyway, then I tried

CREATE UNIQUE INDEX tmpidx ON claim (tpa,pun,grn,claim);

that of course failed, stating dups existed.

Any help would be appreciated.

Thanks,

Jeremy