BuddyPress Followers plugin : https://wordpress.org/plugins/buddypress-followers/
Adds an easy way to follow various users in your BuddyPress profile.
a. Install the above plugin
b. To disable Follow link below instructor in course page
Paste following code in child theme functions.php file.
add_filter('wplms_instructor_meta','wplms_add_follow_button',10,2);
function wplms_add_follow_button($meta,$instructor_id){
$meta .=bp_follow_get_add_follow_button(array('leader_id'=>$instructor_id));
return $meta;
}