Removing viewcontrollers from navigation stack

When session expired move to login page : Removing viewcontrollers from navigation stack

//If session expaired move to login page

if message == "Session Expired" {

    DispatchQueue.main.async {

        //Check navigation stacks

        let navigationArray = self.navigationController?.viewControllers //To get all UIViewController stack as Array

        print(navigationArray!)//Prints navigation stacks

        //Remove all navigations

        self.navigationController!.viewControllers.removeAll()

        //Remoce particular VC navigation

        //self.navigationController?.viewControllers.remove(at: "insert here a number")

        //Check navigation stacks

        let navigationArray2 = self.navigationController?.viewControllers //To get all UIViewController stack as Array

        print(navigationArray2 as Any)//Prints nill

        //Check whether the user logined or not

        UserDefaults.standard.set(false, forKey: "isUserLoggedIn")

        //Clear user defaults

        SharedClass.sharedInstance.clearDataFromUserDefaults()

        let lvc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LVC") as! LoginViewController

        let appDelegate = UIApplication.shared.delegate as! AppDelegate

        appDelegate.window?.rootViewController = lvc                                

    }

}