Delete cookies

To assign a past expiration date on a cookie
Determine whether the cookie exists, and if so, create a new cookie with the same name.
Set the cookie's expiration date to a time in the past.
Add the cookie to the Cookies collection object.
The following code example shows how to set a past expiration date on a cookie.

VB

If (Not Request.Cookies("UserSettings") Is Nothing) Then
    Dim myCookie As HttpCookie
    myCookie = New HttpCookie("UserSettings")
    myCookie.Expires = DateTime.Now.AddDays(-1D)
    Response.Cookies.Add(myCookie)
End If


C#

if (Request.Cookies["UserSettings"] != null)
{
    HttpCookie myCookie = new HttpCookie("UserSettings");
    myCookie.Expires = DateTime.Now.AddDays(-1d);
    Response.Cookies.Add(myCookie);
}