he is ready to leave this county anytime, but can I request the judge to let his leave( deportation ) within a decent manner?)
-Yes. He can tell the immigration judge during the deportation hearing that he will choose volunteer departure and then, he can leave US without force. It is more difficult for the CBP/immigration judge to try to deport someone than try to keep him in this country. So, th eimmigration judge will be happy to see your friend to leave US volunteerly. So, just tell your friend that he is not a criminal and nothing worry too much.
The following is some links about the detainee release on bond for your reference: