Edit / Delete Bill:
For Edit Bill just go to the Menu then Billing then Update Payments then Select the Bill in Payment Updates and click on Changes, you will find page of Create/Edit Bill and there you can directly edit your bill as per requirements. You can also see the Bill Preview on the same page as the changes you do in the bill. Once editing is done, you can click on Update for final bill. See the page given as below.
Navigate - Billing & Receipt(s) ---> Register ---> Edit link, In Bill listing there is Action drop down where you can see Edit button
From the Action drop down you can able to edit, delete, download, send SMS, email also you can Record the payment on respective bill.