Retrieve Data that do not exist in the primary table, exist in the secondary only
Use EXCEPT:

SELECT [id]
  ,[name]
  ,[email]
  ,[phone]
  ,[cellphone]
  ,[none]
FROM [test].[dbo].[datatable1]
EXCEPT
SELECT [id]
  ,[name]
  ,[email]
  ,[phone]
  ,[cellphone]
  ,[none]
FROM [test].[dbo].[datatable]


This will give you all the rows that exists in datatable1 but do not exist in datatable.

If you want it only for the keys then you should use

select t1.[id]
from   [test].[dbo].[datatable1] AS t1
where  not exists (select t2.[id]
                   from   [test].[dbo].[datatable] AS t2
                   where t2.[id] = t1.[id]);