GeoNode has the ability to restrict or allow other users to access a layer.
Go to the layer preview of the first layer uploaded, and copy the URL to that preview page.
The URL should be something like:
Now log out of GeoNode by clicking on your profile name and selecting Log out.
When asked for confirmation, click the Log out button.
Now paste the URL copied about into your browser address bar and navigate to that location.
You will be redirected to the Log In form. This is because when this layer was first uploaded, we set the view properties to be any registered user. Once logged out, we are no longer a registered user and so are not able to see or interact with the layer, unless we log in GeoNode again.