how can i deallocate viewControllers in ios

Question

I made some views ordering like Login -> Navigation Controller[Dashboard -> Detail]

In LoginViewController, There is Login Button and it has Action

@IBAction func loginTapped(_ sender: Any){
    let mainNavigationController = storyboard?.instantiateViewController(withIdentifier: "MainNavigationViewController") as! MainNavigationViewController
    present(mainNavigationController, animated: true, completion: nil)
}

In NagivationController

There are two Views,Dashboard and Detail

Detail View is pushed by segue action from Dashboard

and Dashboard has tab bar Item to logout

I know that when back button is tapped in Detail view, It doesn't deallocating Detail View. It just push back to Navigation Controller's Stack (Is it right...?)

but when i tapped Logout Button in Dashboard, I thought Navigation Controller which contains two views (Dashboard, Detail) should be deallocated

but it doesn't deallocated.

I set the deinit method in Navigation View Controller like this

deinit {
    print("Main Navigation View Controller is deinited")
}

but it never called

How can i deallocate views that appear after login, when i tapped logout button

Sorry for poor syntax in English because i'm not Native