Module for odoo 8 and 11 available on Github.
Some tips found on the web hides only the link from Odoo homepage however URL are still reachable (~/web/database/manager). By installing this module, it will filter the access to Odoo database manager through the controller except connections coming from IPs listed in system parameters.
This module will avoid unwanted connections attempts and secure your database manager access.
Works with NGINX with some modification on nginx config file, click here for more detail.
To disable completely database manager access:
Add list_db = False in odoo.conf / openerp.conf config file.