MySQLi delete in multiply tables

Hi.

In this code

PHP Code:

$tables = array('tasks', 'task_time', 'task_favorites', 'task_subscribers'); 
 $this->db->where('task_id', $task_id);
 $this->db->delete($tables); 


I've got error

Code:

Deletes are not allowed unless they contain a "where" or "like" clause.

What's wrong?

CI version 3.0.1