code: public boolean dropSingleIndex(String indexName) throws
              ElasticsearchException {
          DeleteIndexRequest deleteIndexRequest = new DeleteIndexRequest(indexName);
          DeleteIndexResponse res = this.client.admin().indices().delete(deleteIndexRequest).actionGet();
          return indexExists(indexName);
      }
docs: Drop an ES Index
  
  @param indexName
  @return true if the index exists
  @throws ElasticsearchException