BuddyPress.org

@manni65929 , try this

add_action( 'bp_ajax_querystring', 'user_remove_mem_directory', 20, 2 );
function user_remove_mem_directory( $query, $object ) {
	if ( 'members' != $object ){
		return $query;
	}

	$excluded_user = '1';// admin id to remove from the member directory

	$args = wp_parse_args( $query );

	if ( ! empty( $args['exclude'] ) ) {
		$args['exclude'] = $args['exclude'] . ',' . $excluded_user;
	} else {
		$args['exclude'] = $excluded_user;
	}

	$query = build_query( $args );

	return $query;

}