Only social media login/register

Hi,

I want to allow only login/register through social media. How can I hide “Register” and “Enter” button?
When somebody enter to the website and click into Register button, they automatically create an account with ficticious e-mail and without the information that I want to know about the user… I want to avoid this kind of users.

Could you help me with this?

Thank you

The page I need help with: [log in to see the link]