code: public boolean delete(Marker marker) {
          boolean deleted = false;
          if (contains(marker)) {
              deleted = true;
              ShapeMarkers shapeMarkers = shapeMarkersMap.remove(marker.getId());
              if (shapeMarkers != null) {
                  shapeMarkers.delete(marker);
              }
              marker.remove();
          }
          return deleted;
      }
docs: Get the shape markers for a marker, only returns a value of shapes that
  can be edited
  
  @param marker marker
  @return deleted flag