i want to transfer my apple balance to apple cash card

You cannot transfer money from your Apple ID or iTunes pass to your Apple Cash. You have to meet certain criteria. Go here for assistance - iTunes - Official 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 to request a refund. When you contact Apple, please include the following information:

Your Apple ID. The refund amount. Your current shipping address.