using System;
using System.Linq;
using System.Text;

class Program
{
    private static void Main()
    {
        var replaceCodes = new[] { "rown", "he", " j"};
        var sb = new StringBuilder().Append("The quick brown fox jumps over the lazy dog");
        var outStr = replaceCodes.Aggregate(sb, StringBilderCleaner).ToString();
        Console.WriteLine(outStr);
    }

    static StringBuilder StringBilderCleaner(StringBuilder sbStr, string rmStr)
    {
        var startIndex = 0;
        var inProcces = false;
        for (var i = 0; i < sbStr.Length; i++)
        {
            if (inProcces)
            {
                var l = i - startIndex;
                if (l == rmStr.Length)
                {
                    inProcces = false;
                    sbStr.Remove(startIndex, l);
                }
                else inProcces = rmStr[l] == sbStr[i];
            }
            else
            {
                if (sbStr[i] != rmStr[0]) continue;
                startIndex = i;
                inProcces = true;
            }
        }
        return sbStr ;
    }
}