News Box Manager went from 2.2.1 to 3.0.0 with no in between. Make sure you are talking the correct mod. If you still are sure it's NBM and are concerned about the installation of the DB, check the readme.html in the Docs folder under installation.

It will tell you how to wipe out the old database. Removing other files would involve determining the exact version, downloading it, and using it as a guideline in old file removal.