When you perform the uninstall of Backup Exec it should take care of this for you. I would suggest performing the uninstall of Backup Exec first, then uninstall the remaining SQL parts.
But to remove the database, just follow the first few steps in this technote to detach the database from sql. Also note, if you do this the uninstall of Backup Exec may have some issues as well.
http://support.veritas.com/docs/274102Regards,