Hi there,
I am searching for a way to disable or not load any overlays on an osmdroid map.
The map should only show the outlines of countries and states, rivers and mountains but without any cities, streets or other POIs.
Is this even possible?
Thanks in advance
Without having installed that app, I would say that it is displaying only maps based on single tiles, like osm.org does. Correct me if I am wrong.
So when you need maps in your own style with less details and objects, then have a look at some apps that youse the Mapsforge library, because they can display vector graphic maps. I think you can create mapsforge-maps on your own.
Same fearture has the Osmand app that is under heavy development and progress at this time.
About Osmand, you can download raw OSM data from geofabrik.de or cloudmade etc. for your region. Then do a filterring with osmfilter or osmosis. Finally feed this filtered raw map data to Osmand’s Mapcreator, so you have a vector map with your reduced elements.
Search the OSM wiki about each program I mentioned.
When problems anywhere, come back here and ask 
Stephan