code: synchronized void deleteIndex(PersistentIndex index)
     {
        // remove it from the lists if index is registered
        indexes.remove(index);
        indexNames.removeName(index.getName());
        synchronized (deletable)
        {
           LOG.debug("Moved " + index.getName() + " to deletable");
           deletable.add(index.getName());
        }
     }
docs: Removes the <code>index</code> from the list of active sub indexes. The
  Index is not actually deleted right away, but postponed to the
  transaction commit.
  <br>
  This method does not close the index, but rather expects that the index
  has already been closed.
  
  @param index
  the index to delete.