How can I cash out money from my Apple Account?

This is what your Apple Account can be used for. It is not a cash account where you can transfer funds out of it. You also use this account to redeem Gift Cards and since you cannot redeem a Gift Card for cash, you cannot transfer the money out of there as if it were cash.

What you can buy with your Apple Gift Card or Apple Account balance - Apple Support

Funds in your Apple Account can only be spent with Apple. It cannot be cashed out.