Sorry, it is not possible to restore the manager. If you want to reset the database, please Stop the Output Messenger server service & move the Omls.db3 to some other folder. Then re-install Output Messenger server.
FYI: We have added restriction to delete the Admin User account in our latest Output Messenger Server version (from # v1.0.75) . Hence please upgrade to the latest version, once enabled your admin account.
Hope this helps you.