using System;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

                string json = @"{

   'results':  [

   {'x':'12','tocs':'33,33,33'},

     {'x':'13','tocs':'33,33,33'},

     {'x':'14','tocs':'33,33,33'},

     {'x':'15','tocs':'33,33,33'},

     {'x':'16','tocs':'33,33,33'}]

 }";

var parent = JsonConvert.DeserializeObject<JObject>(json);

((JArray)parent.Property("results").Value)

    .Select(jo => (JObject)jo)

    .ToList()

    .ForEach(x => 

        x

            .Properties()

            .ToList()

            .ForEach(p =>

            {

                if (p.Name != "x")

                    p.Remove();

            }))

    //.Dump();

    ;

        Console.WriteLine( parent.ToString());

    }

}

​

​

​