I would like my apple id balance to be R0

Depending on the amount.

1.

See -> Change your Apple ID country or region

Change your Apple ID country or region - Apple Support (KW)

⤵️

if you have less store credit than the cost of a single item, contact Apple Support.

2.

See -> Check your Apple ID balance

Check your Apple ID balance – Apple Support (UK)

scroll to ⤵️

If you have an 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 the 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 delivery address.

Then ->  contact Apple Support.