Can't turn off signup on community edition - Green button stuck

I cant turn off signup in the admin panel. I need to turn off signup as some users (bullies at school) found my gitlab and created hundreds of users to fill up my storage. The green dot is frozen.
I have also tried editing setting in gitlab.rb. That doesn’t help either.

Help!
I am hosting this on DigitalOcean with the one click install Image.

I ran into the same issue. The settings are found here: http://whateveryoursiteis.com/admin/application_settings

Scroll down to find the checkbox where you can disable sign up.

Literally joined just to say this. Best of luck!