Can I cancel a transfer I already sent?

It depends on how it was sent. A transfer to someone who already has the wallet arrives almost instantly and cannot be reversed once you approve it — so always check the name and amount before you confirm. A payment link is different: you can cancel it any time before it's claimed. On the Payments page, you should see a card that shows “Pending Payment Links”. Tap that card, then select the one matching the amount and time, and cancel it — the money returns to your balance immediately.