DELETE p1
FROM @phonenum p1 
   INNER JOIN @phonenum p2
   ON p1.phone = p2.phone and p1.pdate > p2.pdate  

Declare @phonenum table (phone varchar(10), pdate int) 
 
insert                              --  set up for test
into @phonenum (phone,pdate)
select '1',1 union all
select '2',2 union all
select '3',3 union all
select '3',2 union all
select '4',2 union all
select '5',1 union all
select '5',7 union all
select '5',3 union all
select '6',1 


select 'original table', phone, pdate   -- show before picture
from @phonenum


/*  Remove the dups from the original table based on oldest date */

DELETE p1
FROM @phonenum p1 
   INNER JOIN @phonenum p2
   ON p1.phone = p2.phone and p1.pdate > p2.pdate  

 

select 'after delete', phone, pdate   -- show after picture
from @phonenum