You can write a query for that something like following-
;WITH CTE(emp_name,emp_mail,emp_contact,SlNo)
AS
(
SELECT emp_name,emp_mail,emp_contact,ROW_NUMBER() OVER(PARTITION BY emp_name,emp_mail,emp_contact ORDER BY emp_name,emp_mail,emp_contact) AS SlNo
FROM Demo
)
DELETE FROM CTE WHERE SlNo > 1
For more details please visit my blog post at-
SQL Server: Delete/Update duplicate records | Technology Talks[
^]
Hope, it helps :)