using System;

using System.Data;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var table = new DataTable();

        table.Columns.Add("sno",typeof(int));

        table.Columns.Add("amount",typeof(int));

        table.Rows.Add(new object[]{ 1,12});

        table.Rows.Add(new object[]{ 1,-6});

        table.Rows.Add(new object[]{ 2,10});

        table.Rows.Add(new object[]{ 2,-5});

        table.Rows.Add(new object[]{ 2,-5});

        table.Rows.Add(new object[]{ 3,12});

        table.Rows.Add(new object[]{ 3,-4});

        table.Rows.Add(new object[]{ 3,-4});

        table.Rows.Add(new object[]{ 3,-4});

        var FinalDataTable = table.AsEnumerable()

                        .GroupBy(r => r["sno"])

                        .Where(g => g.Sum(r => (int)r["amount"]) != 0)

                        .SelectMany(r => r)

                        .CopyToDataTable();

        foreach(DataRow row in FinalDataTable.Rows)

            Console.WriteLine($"{row["sno"]} = {row["amount"]}");

    }

}

​

public class Obj

{

    public int sno {get;set;}

    public int amount {get;set;}

}