You can unallocate a customer receipt from a sales invoice in two ways:
Once you unallocate your transactions, the sales invoice becomes outstanding and your customer receipt shows as a payment on account.
If you have multiple receipts allocated to the same invoice, it’s easier to unallocate directly from the customer receipt.
The receipt no longer links to the sales invoice, so you can edit or reverse the invoice. Sage Accounting saves the payment on the customer's account.
Unallocate a customer receipt from a sales quick entry invoice