In order to generate receipt numbers on transactions, we need to create a receipt document in the Communications section of eTapestry. We can delete templates even if they have been used to generate receipt numbers in the past.
Deleting the template that you used to generate a receipt number will not retroactively remove the receipt number from that transaction. However, if you delete the template, you will not be able to receipt future transactions with this template. You can create a new template to receipt future transactions; please see How To Create a Communications Template for information about how to create a new template.