Let's say you get a payment from a client that you've recorded as an 'Offline Payment' on a project, but then you need to remove it.

All you need to do to remove an Offline Payment from the project is to first head to your project, then select the 'Billing' tab

From there you'll be able to see your Payments. You can Edit or Remove Offline Payments by clicking the 'Action Dots' associated with the payment, and finally 'Remove or Edit