- you want to be able to access it, but
- you don't want your users to be able to log in
In that case Forma Lms offers you a useful maintenance mode.
You can find it under Administration>main>settings>settings>advanced
Scroll the page until the end, where you can find the security related settings.
Flag "maintenance mode" and the LMS will be unreachable by users. They'll just see the home page with a sign saying that the site is under maintenance.
You can of course log in just the same. Below the flag I mentioned above, you can find a field where you'll set the password you wish to use.
You'll be able to reach your LMS by accessing an URL like this:
http://elearningplatform.com/index.php? ... aintenance
where the last string of text is the password you've chosen.