code: public void removeTagFromFileModel(FileModel fileModel, String tagName)
      {
          Traversable<Vertex, Vertex> q = getGraphContext().getQuery(TechnologyTagModel.class)
                  .traverse(g -> g.has(TechnologyTagModel.NAME, tagName));
          TechnologyTagModel technologyTag = super.getUnique(q.getRawTraversal());
  
          if (technologyTag != null)
              technologyTag.removeFileModel(fileModel);
      }
docs: Removes the provided tag from the provided {@link FileModel}. If a {@link TechnologyTagModel} cannot be found with the provided name, then this
  operation will do nothing.