To refund a payment, go to your Stripe dashboard and find the payment in question.
Then click on to the right of the payment and then on “Refund charge”. You can then
enter the amount of the refund. If you leave that space empty, the entire amount will be
refunded. Select a reason for the refund and confirm it by clicking on “Refund”.
Unfortunately, if you made a refund by mistake, there is no way to cancel it. Your only
option will be to invoice that amount again.
Read here for information about the other payment options offered (in addition to credit
card payments) and how to activate these.