SautinSoft.HtmlToRtf h = new SautinSoft.HtmlToRtf();
    h.OutputFormat = HtmlToRtf.eOutputFormat.TextUnicode;
    string text = h.ConvertString(htmlString);

public static string StripHTML(string HTMLText)
        {
            Regex reg = new Regex("<[^>]+>", RegexOptions.IgnoreCase);
            return reg.Replace(HTMLText, "");
        }

IHTMLDocument2 htmlDoc = (IHTMLDocument2)webBrowser.Document;
string innerHTML = htmlDoc.body.innerHTML;
string innerText = htmlDoc.body.innerText;

public static string ToMarkDown(this string input)
    {
        var process = new Process();

        process.StartInfo = new ProcessStartInfo("python", "tools/html2text.py")
                                {
                                    RedirectStandardInput = true,
                                    RedirectStandardOutput = true,
                                    UseShellExecute = false,
                                    CreateNoWindow = true,
                                };

        process.Start();

        process.StandardInput.Write(input);
        process.StandardInput.Close();

        string md = process.StandardOutput.ReadToEnd();

        process.WaitForExit();

        process.Dispose();

        return md;
    }

using System;
using System.Text.RegularExpressions;

public static class StringHelpers
{
    public static string StripHTML(this string HTMLText)
        {
            var reg = new Regex("<[^>]+>", RegexOptions.IgnoreCase);
            return reg.Replace(HTMLText, "");
        }
}

var yourHtmlString = "<div class="someclass"><h2>yourHtmlText</h2></span>";
var yourTextString = yourHtmlString.StripHTML();