Drupal 7 Stop User Registration Emails

Using A Module

Mailcontrol

Using Drush

drush vset user_mail_register_no_approval_required_notify FALSE

All Registration Variables

user_mail_register_admin_created_notify
user_mail_register_pending_approval_notify
user_mail_register_no_approval_required_notify
user_mail_password_reset_notify
user_mail_cancel_confirm_notify