In BuddyPress you will see a top navigation bar which is enabled by default.
This might be annoying for some. Some plugins also need this to be disabled. You can disable it appearing everywhere by following method.
Step 1: Open wp-config.php file which is in the root folder of your BuddyPress installation.
Step 2: Add following line in the file
define( ‘BP_DISABLE_ADMIN_BAR’, true );
You can see it live in action (admin bar disabled) on Movie Reviews portal.