If you want to disable registration, but still allow users to log in, follow these steps. You can also leave a custom message for users.
To disable registrations, login as an Admin and go to this address
http://YOURSITEHERE.readingbydesign.org/admin/config/people/accounts
Set the "Who can register accounts?" option to "Administrators only" and click "Save Configuration at the bottom.
Next, go to
http://YOURSITEHERE.readingbydesign.org/admin/structure/block/manage/blo...
Click the "Disable rich text" link below the text entry box field to go into "code view." Then delete everything in that text box.
If you want to leave a custom message, click the "Enable rich text" link below the text box to go back into normal view. Type a message like "Registration is now closed!"
Scroll to the bottom of the page and click the "Save Block" button to save your changes.
Please note: it can take a few minutes for this to "take effect" since our websites are cached for non-logged-in visitors. So if you don't see the changes right away, come back in a few minutes and look again.