LayoutManager is the class that layout views in RecyclerView. So change recyclerView.setLayoutManager(LayoutManager) if you want to change layout. In your case, if you use LinearLayoutManager, do this by calling:

LinearLayoutManager layoutManager = ...
recyclerView.setLayoutManager(layoutManager);

//when you want horizontal
layoutManager.setOrientation(context, LinearLayoutManager.HORIZONTAL);

//when you want vertical
layoutManager.setOrientation(context, LinearLayoutManager.VERTICAL);