Keep one id and remove the duplicate id

Try This. Its will work for you . I have tested

 

 

WITH TempStudent (Id,duplicateRecCount)
AS
(
SELECT Id,ROW_NUMBER() OVER(PARTITION by Id ORDER BY Id)
AS duplicateRecCount
FROM dbo.student
)
--Now Delete Duplicate Records
DELETE FROM TempStudent
WHERE duplicateRecCount > 1

select * from student