This page explains best practices for cleaning up instances after they are no longer needed.
Use Navigator#clearDestinations and Navigator#cleanup when navigation sessions are completed
To prevent memory leaks and ensure proper cleanup, use
Navigator#clearDestinations and Navigator#cleanup after the navigation
session is completed and the Navigator instance is no longer needed. This can be
done when the user has navigated away from the map and when onDestroy() of the
associated activity is invoked.
Clean up GoogleMap elements when they are no longer needed
If your app uses a GoogleMap instance for non-navigation maps experiences, be
sure to clean up this instance when it is no longer needed. For example, clean
up the Polygon, Polyline, and Marker elements associated with GoogleMap by
calling the Polygon#remove, Polyline#remove, and Marker#remove methods,
respectively. Then, to free up the GoogleMap instance after it is not longer
needed, call GoogleMap#clear assign the instance to null.
For more information about using a GoogleMap instance in your app, see
GoogleMap interaction best
practices.