VS 2008 Webbrowser - Set A Cookie To Expire?

Well for who is willing to give this ago, all you need is 1 webbrowser and 1 button. Set the webbrowser to navigate to [URL] and the button goes the code to expire the cookie JSESSIONID which is generated by the website.

Ok the problem is that i can not delete the cookie before it expires so the only way is to set the cookie to expire e.g. webbrowser1.document.cookie.expire -1d Expires can only be used if you dim something as cookie i think.

Things i tried:

Dim cookie = WebBrowser1.Document.Cookie
If Not cookie = "" Then
cookie.Split(";")

[Code]....

This script is the only thing that works but i know nothing about this language but it does work it expires the cookie and the page lets me get another email address BUT it takes many many tries, restarting the debugging ect... because the cookie JSESSIONID is somehow not always in the same possition so when it is not first on the list i think it doesnt work (if you are going to test this you need to wait 2 secs untill the browser realises the cookie expired if more than that then u know u need to re start debugging and try again)

This should be easy but i have no idea where to start:

Do a lop through all cookies in webbrowser.document.cookie and find "JSESSIONID" cookie, expire it by -1d and then add it back to the browser.

or do a lop where the cookie is in the computer, open expire it and reupload.