using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

using System.Text;

​

public class Program

{

  private static readonly Regex regex = new Regex("[^a-zA-Z0-9]");

  public static void Main()

  {

    var samples = new string[] { "Clásica Twin", "Habitación Doble", "Estándar 180° View", "APARTAMENTO SUPERIOR ( 1 HABITACIÓN )" };

    foreach(var sample in samples)

    {

        var bytes = Encoding.UTF8.GetBytes(sample);

        var result  = Encoding.ASCII.GetString(bytes)

            .Replace("??", string.Empty);

        //var result = regex.Replace(sample, string.Empty);

        Console.WriteLine("{0} == {1}", sample, result);

    }

  }

}

​