To do this task
Go to the Reports menu, choose Sales, and then click Pending Sales.
In the report, find the pending sale that you want to mark as final.
Double-click the line in the report to open the sale.
Go to the Edit menu and choose one of these commands:
For an invoice, choose Mark Invoice as Final.
For a sales receipt, choose Mark Sales Receipt as Final.
For a credit memo, choose Mark Credit Memo as Final.
Save the transaction.