If there's a mistake with a payment, you can do one of two things: archive it, or edit it!
Archiving will be the preferred option if you want to remove it entirely. However, if you made a mistake by putting the wrong amount in the payment source field, or applying it to the wrong invoice, this can be fixed by editing it!
Editing a payment
Find the payment you wish to edit. This can be found in one of two places—either via the Payments tab:
Or it can be found on the invoice it's been allocated to, at the bottom:
Once you've selected the payment you want, click the Edit button at the top:
You'll be able to edit any of the fields on the payment:
You can change the payment source, change the payment amount, change the date, and even remove the payment from this invoice and apply it to a different one, in the event this payment was applied to the wrong invoice!
When you're finished, hit Save payment, and you're all set!