I need to cancel i tunes gift card and refund amount 200 usd to my bank again

No, that is not possible.

If you already use your Apple Account balance, the Apple Gift Card or App Store & iTunes gift card is automatically added to your Apple Account balance.

See -> Check your Apple Account balance -> Check your Apple Account 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 ID 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.

Click here for more support and assistance.