using System;

using System.Collections.Generic;

using System.Text;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string pattern = @"([""'])(?:(?=(\\?))\2.)*?\1";

        List<string> lines = new List<string>(); 

        lines.Add("4121,6383,0,,,TRUE");

        lines.Add("4122,6384,0,\"20,000 BONUS POINTS\",,TRUE");

        lines.Add("4123,6385,,,,");

        lines.Add("4124,6386,0,,,TRUE");

        lines.Add("4125,6387,0,,,TRUE");

        lines.Add("4126,6388,0,,,TRUE");

        lines.Add("4127,6389,0,,,TRUE");

        lines.Add("4128,6390,0,,,TRUE");

​

        StringBuilder sb = new StringBuilder();

        foreach (var line in lines)

        {

            sb.Append(Regex.Replace(line, pattern, m => m.Value.Replace(",", ""))+"\n");

        }           

        Console.WriteLine(sb.ToString());

    }

}