using System;

using System.Text.RegularExpressions;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

            string blacklistHtmlTagsForXSS = @"\<[\s\t\/]*" + string.Join(@"[^>]*\>|\<[\s\t\/]*", new List<string>

            {

                "script",

                "applet"

            }) + @"[^>]*\>";//@"\<[\s\t\/]*script[^>]*\>"

        var inputString = @"<inlinebutton>test</inlinebutton>((\&lt;inlinebutton\&gt;  test2 \&lt;/inlinebutton\&gt;))";

        var inputString1 = Regex.Replace(inputString, @"((\<inlinebutton\>)([\s\S]*?)(\<\/inlinebutton\>))", "", RegexOptions.IgnoreCase);

         Console.WriteLine(inputString1);

    }

}