title: delete cookies during page change , page close and page load
body: <p>i wanted to delete all my cookies in these events.Some says that by setting the cookie expire date to NULL or -1 will work.
  i tried setting them and close the page and re-open the page again. but the cookie is still there.
  i have checked the cookie status and it is shown session instead of expire date.</p>
  
  <p>and cookies expired it will automatically delete from client side?or it is visible but unusable?</p>