var ctrlMan = m_Map.GetCtrlMan();
    var layerMan = ctrlMan.GetLayerMan();    
    layerMan.ClearLayer(); 

    CXCtrlMan ctrlman = m_Map.GetCtrlMan();
    CXLayerMan layerman = ctrlman.GetLayerMan();
    CXLayer layer = layerman.FindLayer(1);
    if (layer) { 
        layerman.ClearLayer(); 
    }