admins.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.DirectoryServices;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DirectoryEntry localMachine = new DirectoryEntry("WinNT://" + Environment.MachineName);
            DirectoryEntry admGroup = localMachine.Children.Find("administrators", "group");
            List<string> adminUsers = new List<string>();
            object members = admGroup.Invoke("members", null);
            foreach (object groupMember in (IEnumerable)members)
            {
                DirectoryEntry member = new DirectoryEntry(groupMember);
                adminUsers.Add(member.Name);
                Console.WriteLine(member.Username); 
            }
            adminUsers.Sort();
            foreach (var user in adminUsers)
            {
                Console.WriteLine(user);
            }
        }
    }
}