Return my App Store Credit to the original gift card

click here ➜ Check your Apple Account balance - Apple Support

If you have Apple Account balance that you can't use

You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards, or unused Apple Account 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, include the following information:

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

Normally once funds are in Apple Account balance the only way to get them out again is to spend them, but a Community Specialist in this topic --> I made a deposit to my Apple account by m… - Apple Community recommends contacting Apple about your options:

Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world."

Click here --> Contact Apple for support and service - Apple Support