BuddyPress.org

Ok, in your plugins directory, create a file called bp-custom.php or “if you have one all ready” add this line to it

add_filter('show_admin_bar', '__return_false');

that should be inside php tags or it wont work. Like this

<?php 
/* Inside with any other code you might have in this file */
add_filter('show_admin_bar', '__return_false');

?>