How to remove a cookie from CookieCollection?

This is my code. It is get/set/remove multiple cookies at once. Set and remove (all) works fine but I can't remove just an expired cookie from CookieCollection.

using System;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;
using System.Web;
using Newtonsoft.Json;

namespace SetGetMultipleCookies
{
    public partial class GetSetCookiesForm : Form
    {
        string readCookiesUrl = "http://test.dev/_test/cookies/readcookie.php";
        string setCookiesUrl = "http://test.dev/_test/cookies/setcookie.php";
        CookieContainer cookieHeader = new CookieContainer();
        CookieCollection cookie_collection = new CookieCollection();

        public GetSetCookiesForm()
        {
            InitializeComponent();
        }

        private void getCookiesButton_Click(object sender, EventArgs e)
        {
            // begins variable for page content.
            string pageSource;
            // send url request to web page.
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(this.readCookiesUrl);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            foreach (Cookie each_cookie in this.cookie_collection)
            {
                if (!each_cookie.Expired)
                {
                    request.Headers.Add("Cookie", each_cookie.ToString());
                } else
                {
                    // how to remove an expired cookie from cookie collection?

                }
            }

            // read the page content
            using (StreamReader sr = new StreamReader(response.GetResponseStream()))
            {
                pageSource = sr.ReadToEnd();
            }

            // display debug.
            resultBox.Text = pageSource + "\r\n";
            foreach (Cookie each_cookie in this.cookie_collection)
            {
                resultBox.Text += each_cookie.ToString() + "; expires=" + each_cookie.Expires + "; path=" + each_cookie.Path + ";domain=" + each_cookie.Domain + "\r\n";
                if (each_cookie.Expired)
                {
                    resultBox.Text += "cookie expired.\r\n";
                }
            }
        }

        private void setCookiesButton_Click(object sender, EventArgs e)
        {
            // send url request to set cookie.
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(this.setCookiesUrl);
            request.Method = "GET";
            request.CookieContainer = this.cookieHeader;
            request.ContentType = "application/x-www-form-urlencoded";
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            // set cookies
            this.cookie_collection = response.Cookies;
            // debug
            resultBox.Text = "Headers ==========\r\n";
            foreach (string each_header in response.Headers)
            {
                resultBox.Text += each_header + " = " + response.Headers[each_header] + "\r\n";
            }
            resultBox.Text += "\r\nCookies (" + response.Cookies.Count + ") ==========\r\n";
            foreach (Cookie each_cookie in response.Cookies)
            {
                resultBox.Text += each_cookie.ToString() + "\r\n";
                resultBox.Text += each_cookie.Name + "\r\n";
                resultBox.Text += each_cookie.Value + "\r\n";
                resultBox.Text += each_cookie.Expires + "\r\n";
                resultBox.Text += each_cookie.Path + "\r\n";
                resultBox.Text += each_cookie.Domain + "\r\n";
                resultBox.Text += each_cookie.Secure + "\r\n";
                resultBox.Text += each_cookie.HttpOnly + "\r\n";
                resultBox.Text += each_cookie.Expired + "\r\n";
                resultBox.Text += "\r\n";
            }
            // get response body.
            using (Stream responseStream = response.GetResponseStream())
            {
                StreamReader reader = new StreamReader(responseStream, Encoding.GetEncoding("utf-8"));
                String responseText = reader.ReadToEnd();
                // json decode
                //LoginResponse responsej = JsonConvert.DeserializeObject<LoginResponse>(responseText);
                // display debug.
                resultBox.Text += "Response body ==========\r\n";
                resultBox.Text += responseText + "\r\n";
            }
        }

        private void removeCookiesButton_Click(object sender, EventArgs e)
        {
            this.cookieHeader = new CookieContainer();
            this.cookie_collection = new CookieCollection();

            resultBox.Text = "Logged out.";
        }
    }
}

In the getCookiesButton_Click method, I just want to remove an expired cookie from CookieCollection. How to do that? How to remove an expired cookie from CookieCollection?

In the red rectangle line, that is the expired cookie first time when click on Get cookies it is showing there with expired report which is correct but second time it should be removed completely from the CookieCollection.

Solution

Found the fixed.

using System;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.IO;
using Newtonsoft.Json;

namespace SetGetMultipleCookies
{
    public partial class GetSetCookiesForm : Form
    {
        string readCookiesUrl = "http://test.dev/_test/cookies/readcookie.php";
        string setCookiesUrl = "http://test.dev/_test/cookies/setcookie.php";
        CookieContainer cookie_container = new CookieContainer();
        CookieCollection cookie_collection = new CookieCollection();


        public GetSetCookiesForm()
        {
            InitializeComponent();
        }


        private void getCookiesButton_Click(object sender, EventArgs e)
        {
            // begins variable for page content.
            string pageSource;
            // send url request to web page.
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(this.readCookiesUrl);
            request.CookieContainer = this.cookie_container;
            request.UserAgent = "My C# App";

            // get response.
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            // reset cookie collection.
            this.cookie_collection = new CookieCollection();
            // loop through cookie container to set only non-expired to cookie collection.
            var cookies_container = this.cookie_container.GetCookies(new Uri(this.readCookiesUrl));
            foreach (Cookie each_cookie in cookies_container)
            {
                if (!each_cookie.Expired)
                {
                    this.cookie_collection.Add(each_cookie);
                }

            }

            // read the page content
            using (StreamReader sr = new StreamReader(response.GetResponseStream()))
            {
                pageSource = sr.ReadToEnd();
            }

            // display debug.
            resultBox.Text = pageSource.Replace("\n", "\r\n") + "\r\n";
            resultBox.Text += "\r\nCookies (" + this.cookie_collection.Count + ") ==========\r\n";
            foreach (Cookie each_cookie in this.cookie_collection)
            {
                resultBox.Text += each_cookie.ToString() + "; expires=" + each_cookie.Expires + "; path=" + each_cookie.Path + ";domain=" + each_cookie.Domain + "\r\n";
                if (each_cookie.Expired)
                {
                    resultBox.Text += "cookie expired.\r\n";
                }
            }

            // clear memory.
            pageSource = default(String);
            request = default(HttpWebRequest);
            response = default(HttpWebResponse);
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }


        private void setCookiesButton_Click(object sender, EventArgs e)
        {
            // send url request to set cookie.
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(this.setCookiesUrl);
            request.Method = "GET";
            request.CookieContainer = this.cookie_container;
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = "My C# App";
            // get response.
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            // set cookies collection
            this.cookie_collection = response.Cookies;

            // debug
            resultBox.Text = "Headers ==========\r\n";
            foreach (string each_header in response.Headers)
            {
                resultBox.Text += each_header + " = " + response.Headers[each_header].Replace("\n", "\r\n").Replace("\r", "\r\n") + "\r\n";
            }
            resultBox.Text += "\r\nCookies (" + this.cookie_collection.Count + ") ==========\r\n";
            foreach (Cookie each_cookie in this.cookie_collection)
            {
                resultBox.Text += each_cookie.ToString() + "\r\n";
                resultBox.Text += each_cookie.Name + "\r\n";
                resultBox.Text += each_cookie.Value + "\r\n";
                resultBox.Text += each_cookie.Expires + "\r\n";
                resultBox.Text += each_cookie.Path + "\r\n";
                resultBox.Text += each_cookie.Domain + "\r\n";
                resultBox.Text += each_cookie.Secure + "\r\n";
                resultBox.Text += each_cookie.HttpOnly + "\r\n";
                resultBox.Text += each_cookie.Expired + "\r\n";
                resultBox.Text += "\r\n";
                // add cookie to cookiecontainer
                this.cookie_container.Add(each_cookie);
            }
            // get response body.
            using (Stream responseStream = response.GetResponseStream())
            {
                StreamReader reader = new StreamReader(responseStream, Encoding.GetEncoding("utf-8"));
                String responseText = reader.ReadToEnd();
                // json decode
                //LoginResponse responsej = JsonConvert.DeserializeObject<LoginResponse>(responseText);// too lazy to do this.
                // display debug.
                resultBox.Text += "Response body ==========\r\n";
                resultBox.Text += responseText + "\r\n";
                // clear memory.
                reader = default(StreamReader);
                responseText = default(String);
            }

            // clear memory.
            request = default(HttpWebRequest);
            response = default(HttpWebResponse);
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }


        private void removeCookiesButton_Click(object sender, EventArgs e)
        {
            this.cookie_container = new CookieContainer();
            this.cookie_collection = new CookieCollection();

            resultBox.Text = "Logged out.";

            // clear memory.
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }
    }
}