code: @Override
      public void unindexHelpModule(HelpModule helpModule) {
          try {
              log.info("Removing index for help module " + helpModule.getLocalizedId());
              Term term = new Term("module", helpModule.getLocalizedId());
              writer.deleteDocuments(term);
              writer.commit();
              indexTracker.remove(helpModule);
          } catch (IOException e) {
              MiscUtil.toUnchecked(e);
          }
      }
docs: Removes the index for a help module.
  
  @param helpModule Help module whose index is to be removed.