Remove register link from /wp-login.php

I am running a multi site and would like to remove the "register" link from all login pages. Currently if I click the register link on this page: http://myinsurancepage.com/wp-login.php it redirects me to our main site and gives a sign up option: http://naoia.com/wp-signup.php.

At this time I don't want to give users the ability to register a username or a site. We are running the M2 plugin and want all users to sign up for a paid membership here: http://naoia.com/join/ (this is currently on free memberships because we are still building and trouble shooting).

In the future we would like to offer members to create sites but it will be for an additional membership level and more of a cost.

Thanks,
William