When working on multiple sites and multiple instances of a site more than once, you’ll need to give yourself administrative permissions to the Drupal interface. Rather than tracking down someone who has rights to the site and have them give you permissions why not just use Drush? Drush makes adding users and giving users specific roles such as administration extremely simple.
From the command line after SSH’ing into your site:
That’s it. Create a user in Drupal and give them administer rights using Drush.