Who do you cancel a payment

We need a LOT more context. Pay to whom? For what?

If you mean an app purchase or subscription, you can't cancel, you can only request a refund:

Here's how to request an app or media refund from Apple (From: Request a refund for apps or content that you bought from Apple - Apple Support - see the article for more detail.)

1. Sign in to https://reportaproblem.apple.com

2. Tap or click "I'd like to," then choose "Request a refund."

3. Choose the reason why you want a refund, then choose Next.

4. Choose the app, subscription, or other item, then choose Submit.

If you were charged for a subscription that you no longer want, you can also cancel the subscription using the directions in this article --> If you want to cancel a subscription from Apple - Apple Support

How you dispute a payment made with Apple Pay depends upon the means of transaction.

For payments made with Apple Pay Cash with Messages, see the section about "How to cancel or dispute a payment" [made with Apple Pay Cash]" by clicking on the link for this document: Send, receive, and request money with Apple Pay - Send and receive money with Apple Cash - Apple Support

"How to cancel or dispute a payment [made with Apple Pay Cash]

1. Open the Messages app, then open the conversation and tap the payment.

2. Your Apple Cash card will open in the Wallet app. Under Latest Transactions, tap the payment, then tap it again.

3. Tap Cancel Payment."

Notes:

- If you don't see Cancel Payment, the person has already accepted the payment. Try asking the recipient to send the money back to you instead.

- It can take 1-3 business days for the money to be refunded, depending on your bank or card issuer.

- Apple Pay person to person payments are just like any other private transaction between two people. If you're unable to cancel or receive your money back from the recipient, you can contact [Apple] to open a dispute [ https://getsupport.apple.com/?caller=kbase&PGF=PGF90000&category_id=SC0287&symptom_id=23288 ].

Get a refund for purchases made with credit or debit cards using Apple Pay --> Get a refund for purchases made with credit or debit cards using Apple Pay - Apple Support

See your Apple Pay transaction history - Apple Support

Dispute a credit or debit card charge made using Apple Pay

If you need to dispute a charge made using Apple Pay, contact your bank or card issuer.

For payments made with Apple Pay see the section about "Report a transaction with the wrong merchant name or location" by clicking on the link for this document: How to use Apple Pay - Make purchases using Apple Pay - Apple Support

"Report a transaction with the wrong merchant name or location

1. On your iPhone, open the Wallet app and tap the card that you made the transaction with.

2. Under Latest Transactions, tap the transaction that you want to report.

3. Tap Report an Issue.

4. Under Issue, tap Incorrect Merchant Info, then tap Merchant Name, Merchant Category, or Other Issue."