How is drupal able to see a module even when I renamed it
Drupal stores information about where to find module files in the system and registry tables.  If you want to revert an update, you'll have to replace the updated version with the old version. If you ran database updates to update the module, you'll have to disable and uninstall it first, and then re-enable it after you've replaced the module files.

If you've removed the module without disabling it, the site should break. If it's still running with the updated module, there must be another copy of it somewhere. 

If you want to know where drupal's reading the files from you can run the following SQL on the db:

SELECT filename FROM system WHERE name = 'mediabox';