This is probably not the simplest solution, but if you won't find anything else: you could setup a reverse proxy between odoo and your users (so that they must use the proxy to access the odoo). Then you add a rule in the proxy, that urls with 'debug=' in them are forbidden.

However, I think there must be a simpler solution.

As a side mark: it is extremely dangerous to change the admin user. Create a custom admin user, if you want to restrict some access, but don't change the default one.

please check this answer -> https://www.odoo.com/forum/help-1/question/how-to-disable-developer-mode-or-debugging-feature-in-openerp-7-10806