How to remove duplicate rows with the same column in SQL

I have the following table in SQL:

I want to remove rows with the same id value.

Which query in SQL should I use?

The table should be as follows after the delete operation:

You could select all unique ids by using group by:

Select 
   max(a)
   ,id
   from Table
   group by id

If the above result is the result that you want to keep in your table then you could just do that:

delete FROM Table
  where a not in (
    Select max(a)  from Table
    group by id
  )