To delete the acknowledgement for multiple transactions: 
  1. Click Marketing and Communications 
  2. Click Acknowledgements
  3. Click the History Tab
  4. Click the drop down arrow next to the most recent output
  5. Click Clear Results.  Do not click Delete as that will delete the history of the process without clearing the results, thus all of the revenue in that process will still be marked as acknowledged and will not pull into the Acknowledgement process again.  If you have clicked Delete by mistake and want to pull this revenue back into the Acknowledgements process, you can use a query to locate the revenue and manually change the revenue to unacknowledged.
Note: When you clear results, the output and merged documents are deleted, the acknowledgement date is deleted on the revenue, and the acknowledgement status becomes Not acknowledged on the revenue.

To delete the acknowledgement for one transaction: 
  1. Go to Revenue > Transaction search.  Search for and select the payment that was acknowledged
  2. Select the letters tab
  3. Highlight the letter and click delete
  4. Select Yes to the message "Are you sure you want to delete this letter?"