How to hide your wp-admin login page?
Change YOURSECRETWORDHERE to something else. It can be any word you want. Just make sure it

How to hide default menu of buddypress
When using buddypress with Wordpress MU, you will find that buddypress adds a default menu bar to your site, like this:

If you want to hide that menu, just add the following like in your wp-config.php
define( ‘BP_DISABLE_ADMIN_BAR’, true );
The menu bar will be disabled, even if you are logged in or out.