code: public function delete($id=false, $index, $type, array $options = array()) {
  		$params = array( '_id' => $id, 
     					     '_index' => $index, 
  					     '_type' => $type);
  
  		foreach ($options as $key => $value) {
  			$params['_' . $key] = $value;
  		}
  
  		$operation = array(
  			array('delete' => $params)
  		);
  		$this->operations[] = $operation;
  		return $this;
  
  	}
docs: delete a document
  
  @param mixed $id
  @param string $index Index
  @param string $type Type
  @param array $options Parameters to pass to delete action
  @return \Elasticsearch\Bulk