Logs out the user.
Assembly: System.Web.Extensions (in System.Web.Extensions.dll)
After you call this method, the current user is no longer authenticated for client application services. This means that you cannot retrieve roles through the ClientRoleProvider class and settings through the ClientSettingsProvider class. However, because the user might have a valid Windows identity, you might still receive a true value from code such as the following: Thread.CurrentPrincipal.Identity.IsAuthenticated. To determine whether the user is authenticated for client application services, confirm that the Identity property value of the IPrincipal retrieved through the static CurrentPrincipal property is a ClientFormsIdentity reference. Then, check the ClientFormsIdentity::IsAuthenticated property.
To reauthenticate the current user, call the ClientFormsAuthenticationMembershipProvider::ValidateUser method or the static Membership::ValidateUser method.