Can I reset the index numbers?

Sorry if this seems trivial, but I made a few test forums on a site in my network, but after I remove them, the number doesnt get dropped back to reflect it, not even if I deactivate the plugin, delete and reinstall the plugin from a backup, and delete and recreate the site. That system will be fine now that i know about it, but for backend cleanliness, I'd like to start fresh for network planning. I deleted all forums for now in case deleting a whole folder would help. Is this possible?