src/Config/Migration/Version0_15_0.php
public function down(Schema $schema)
    {
        switch ($this->platform->getName()) {
            case 'postgresql':
                $this->addSql('DROP SEQUENCE ds_config_id_seq CASCADE');
                $this->addSql('DROP TABLE ds_config');
                break;

            default:
                $this->abortIf(true,'Migration cannot be executed on "'.$this->platform->getName().'".');
                break;
        }
    }
public function down(Schema $schema)
    {
        switch ($this->platform->getName()) {
            case 'postgresql':
                $this->addSql('DROP SEQUENCE ds_config_id_seq CASCADE');
                $this->addSql('DROP TABLE ds_config');
                break;

            default:
                $this->abortIf(true,'Migration cannot be executed on "'.$this->platform->getName().'".');
                break;
        }
    }
Down migration

@param \Doctrine\DBAL\Schema\Schema $schema