Unfortunately that was not possible to turn off from the email section.

But you can try following 2 method :
1. Remove the code from this following files
JoomlaFolder\components\com_easysocial\themes\wireframe\emails\html\registration\approved.php
JoomlaFolder\components\com_easysocial\themes\wireframe\emails\html\registration\auto.php
JoomlaFolder\components\com_easysocial\themes\wireframe\emails\html\registration\login.php
JoomlaFolder\components\com_easysocial\themes\wireframe\emails\html\registration\reactivate.php
JoomlaFolder\components\com_easysocial\themes\wireframe\emails\html\registration\verify.php

                                <td valign="top" style="text-align:left;padding: 10px 0;font-size:12px;">

                                    <a href="<?php echo FRoute::users( array( 'external' => true ) );?>" style="text-decoration:none;color:#00aeef;">

                                        <?php echo JText::_( 'COM_EASYSOCIAL_EMAILS_FIND_FRIENDS' ); ?>

                                    </a>

                                    <p style="margin: 5px 0 0;color:#888;">

                                        <?php echo JText::_( 'COM_EASYSOCIAL_EMAILS_FIND_FRIENDS_DESC' ); ?>

                                    </p>

                                </td>

2. Or you can create a hidden menu from Easysocial - users page, and set this menu only SuperUser can access, you can refer on my attached screenshot below.