Doctrine 1.2 How to drop non standard index in migration

version73.php

<?php
/**
 * This class has been auto-generated by the Doctrine ORM Framework
 */
class Version73 extends Doctrine_Migration_Base
{
    public function up()
    {
        $manager = Doctrine_Manager::getInstance();
        
        // by default index name will be formated and _idx suffix is added. Sometimes this could be forced
        $manager->setAttribute(Doctrine_Core::ATTR_IDXNAME_FORMAT, '%s');
        
        $this->removeIndex('internship', 'name');
        
        
        
    }

    public function down()
    {
        $manager = Doctrine_Manager::getInstance();
        
        $manager->setAttribute(Doctrine_Core::ATTR_IDXNAME_FORMAT, '%s');
        
        $this->addIndex('internship', 'name', array(
            'fields' => 
             array(
              0 => 'name',
             ),
            'unique' => true
        ));
        
    }
}