You can remove/delete Auto Number Helper from the fields where you created the Auto Number Helper.
Steps to Remove Configured Field:
- Go to the Auto Number Helper App and click on the About Auto Number Helper tab.
- Select Step 1 > click on Recycle Bin icon against the row which you want to remove.

- Review and confirm the warning popup

- Now you can see the configured field is successfully removed.
P.S. Discover Auto Number Helper, the simple way to update Auto Number values in Salesforce. Find it on AppExchange - https://appexchange.salesforce.com/appxListingDetail?listingId=a0N30000000puTcEAI