I have never seen documentation for that. I think you will need to reach out to Xerox support. The have knowledge of the SQL database and can most likely help you to clean it out.
The alternative would be to back up your workflows (not a clone though - because a clone will capture some of the database information). Then you could uninstall Core, Uninstall and remove all the SQL database components. Then you could reinstall Core from scratch with a brand new clean database.
I always make sure that after you get a 'clean' install going that you create an 'empty' Clone file. This way you can restore the clone file in the future which should also 'reset' the database and then import workflows. And you can also create a clone after all the workflows are imported and working again. This is the fastest way to 'reset' the database that I know.