The LoginStatus.LoggingOut event is raised on the server when the user clicks the logout link. The logout process does not occur until after this event, and user information is still available.
The LoginStatus.LoggingOut event allows you to cancel the logout process if the user must complete an activity before leaving the Web site, such as purchasing items in a shopping cart or submitting changes to a database. You can cancel the LoginStatus.LoggingOut event by setting the LoginCancelEventArgs.Cancel property of the System.Web.UI.WebControls.LoginCancelEventArgs parameter to true.
Use the LoginStatus.LoggingOut event to provide additional processing, such as clearing per-user data, before a user logs out of a site.