The legacy web client app, also known as Dynamics 365 – custom, can be hidden from end users.
On the other hand I noticed that the application is still accessible via the following URL:
By contacting Microsoft support, I’ve been confirmed that this is by design, as of now there are no plans to completely restrict users from accessing the default app – it can be hide for end users but will be still accessible through direct URL.
As a workaround to this limitation, I changed the default app to show nothing but a single HTML web resource displaying an announcement asking people to use the new application and save the right URL in their favorites.
In your sitemap, you need to keep the setting Area, otherwise you would no longer be able to access Advanced settings.
Finally, I want to thank Animesh R. for his kind and generous contribution. Feel free to share your ideas for other workaround and don’t forget to vote for the idea. Thanks.