PostgreSQL: deleting duplicates example

delete from resource_db.ht_sim_party where sim_party_id in (
 select sim_party_id from (
  select sim_party_id, sim_id, party_id, rnum from (
   select distinct sim_party_id, sim_id, party_id, row_number() over (partition by party_id) as rnum from resource_db.ht_sim_party 
   where ht_sim_party.from_date <= localtimestamp(0) and localtimestamp(0) < ht_sim_party.to_date
   and '2016-05-30' < ht_sim_party.from_date
  ) as foo 
  where rnum > 1
 ) as bar
)