using System;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string inputJson = @"

        {

            ""obj"": {

                ""w"": null,

                ""x"": """",

                ""y"": ""test str"",

                ""Z"": ""N/A""

            },

            ""myStr"": ""Hi""

        }";

​

        var jo = JObject.Parse(inputJson);

​

        var unwantedProperties = jo.Descendants()

            .OfType<JProperty>()

            .Where(p => p.Value.Type == JTokenType.Null ||

                   (p.Value.Type == JTokenType.String &&

                    ((string)p.Value == string.Empty ||

                     string.Equals((string)p.Value, "N/A", StringComparison.OrdinalIgnoreCase))))

            .ToList();

​

        foreach (var prop in unwantedProperties)

        {

            prop.Remove();

        }

​

        string outputJson = jo.ToString(Formatting.None);

​

        Console.WriteLine(outputJson);

    }

}

​