Remove Date overlap duplicates

I have a table containing following data.

ID   Start_date         End_date
1    20-OCT-2005     31-DEC-2005
1    01-NOV-2005    31-JAN-2006
2    01-JAN-2005     31-JAN-2005
2    01-JAN-2005     31-DEC-2006

Now I need to update the start date of 2nd Row as '01-jan-2006' and I also need to delete the 3rd row.
In a nut shell, I need to remove the duplicate data either by updating or by deleting.
Is there any way to do it using PL/SQL? Received on Mon Oct 05 2009 - 01:11:14 CDT