Glad to have you join the Community. I'll be happy to assist you with canceling a payment and crediting it to another invoice.
Before we start, I've got a few questions that'll help me understand this situation better. Are you using Online Payments? If so, are you looking to reverse that payment back to the customer's card? If not, I recommend opening up the invoice with the payment > click on the blue link which says Payment made at the top right. Once you've got the payment open > click Clear Payment > Save and Close.
After this, open up the invoice you'd like to apply the payment to > Receive Payment > scroll down and you should see the payments associated with that customer > attach the payment > hit Save and Close. Try this out and let me know if this works for you. I'll be on standby. :)
Thanks for joining the thread. Your situation sounds a bit different than the original poster's question. That's okay, I'll help you get back on track.
It sounds as though you need to delete a payment that was linked to an invoice by mistake. Don't worry, the process is quick and simple.
Here's how to delete a payment:
1. Click the Sales tab, then select Invoices.
2. Click on the invoice.
3. Select "1 payment made" at the top right corner of the page.
4. Click More at the bottom of the page, then click Delete.
Next, you can apply the payment to the proper customer's invoice. Here's how to do that: Record invoice payments in QuickBooks Online.
If you have any other questions, or if I haven't quite hit the mark in my response, please reach out to our tech support team.
Have a great day!