duplicate rows

Hi ,

I have to delete the duplicate rows by checking the created date .  Means if there are two rows for particular key_id , I have to remove the older record by checking the created date .The latest record data  I have to keep in table . Here the key_id and created is the composite primary key.

Here IS MY TABLE DESCRIPTION

SQL> desc prod.f0784
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 key_id                               NOT NULL NUMBER(20)
 rate                                 NOT NULL NUMBER(38)
 location                                      NUMBER(6)
 member                                        NUMBER(6)
 created_date                         NOT NULL DATE

Please help  help for sql query

Thanks!