Clear persistent login tickets in ASP.NET

ClearPersistentCookies.cs

private void ClearAnyPersistentCookies() {
	var cookie = Request.Cookies.Get(FormsAuthentication.FormsCookieName);
	if (cookie == null) return;
	
	var ticket = FormsAuthentication.Decrypt(cookie.Value);
	if (ticket == null) return;
	
	if (ticket.IsPersistent)
		FormsAuthentication.SignOut();
}