Making sure that the views and view models in your subregion implement INavigationAware or IConfirmNavigationRequest will allow Prism to automatically call their OnNavigatedFrom/OnNavigatedTo methods during navigation. This is a more elegant way to take advantage of Prism's built-in navigation and region lifecycle management. To handle the subregion lifecycle consistently with the parent view and make your code cleaner and easier to maintain, think about utilizing scoped regions or navigation-aware actions rather than manually deleting views.