The action that adds the menu bar is:
add_action( 'admin_bar_menu', 'wpseo_admin_bar_menu', 95 );
It's in the file:
/inc/wpseo-non-ajax-functions.php
I tried remove_action but had no success in removing it.
http://codex.wordpress.org/Function_Reference/remove_action
If it's holding you up, perhaps for now just comment out the action.
Note: As far as I can tell the menu only appears to those for whom current_user_can( 'manage_options' ) == true. It should not render for anyone else.
