Undoing a payment in Allmoxy as well as refunding the money via Stripe
If you need to undo a payment in Allmoxy (in other words, you need Allmoxy to reflect that the amount actually still needs to be paid) - you can go to Reports (the pie-chart icon) -> Financial Reports -> Transaction History. On this transaction history page you will be able to filter the report by the dates and type of payments. Then when you hover over the payment you'd like to undo, you'll see a little arrow to undo the payment.
In addition to doing this, you'll likely need to actually refund the money you've received. You'll do this by going to your own Stripe dashboard and signing in (you only have one log-in for your whole company, which was created when you connected your site to Stripe). That's when you'll find the payment, click on it, and use the 'refund' feature.