Cancel request at any time during a flow

I am currently designing a payment flow for a mobile app. The flow is divided in 5 steps :

  1. Choose account
  2. Scan QR Code
  3. Enter amount + Memo
  4. Fees
  5. Review & send

While I was designing it, I told myself, what if the user wants to cancel everything and go back to the Dashboard. As of today, I have no Cancel button on my flow but go back buttons obviously.

What do you think about it ? Should I add a Cancel button, or I should let the user close the app and re-open it?

Thanks

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