How can I withdraw my apple id balance?

Normally once funds are in Apple Account balance the only way to get them out again is to spend them.

From: Check your Apple ID balance - Check your Apple Account balance - Apple Support -->

"About unused Apple ID balance

You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards, or unused Apple ID balance for cash, except as required by law. If your jurisdiction allows for refund of redeemed gift balances, you can contact Apple Support." Read the support article for more details.

I do not believe this is possible except for certain situations where it is required by law. If you believe this is one of those situations then contact Apple Support. It is also worth noting that you cannot transfer your credit to another person or account.