Hi John,

Thank you for the question.

Please use the following code.

/**
 * Removes the 'friends' sub nav from activity.
 */
add_action( 'bp_activity_setup_nav', function () {

	if ( ! bp_is_active( 'friends' ) ) {
		return;
	}

	bp_core_remove_subnav_item( bp_get_activity_slug(), bp_get_friends_slug() );
} );

/**
 * Removes 'friends' from account drop down menu in the admin bar.
 */
add_action( 'bp_activity_setup_admin_bar', function () {

	if ( ! bp_is_active( 'friends' ) ) {
		return;
	}

	global $wp_admin_bar;
	$wp_admin_bar->remove_node( 'my-account-activity-friends' );
} );

Regards
Brajesh