add_filter( 'views_edit-shop_order', 'wc_hide_completed_link', 10, 1 );
function wc_hide_completed_link ($views) {
	$views['exclude-completed'] = sprintf('<a href="edit.php?exclude_order_status=wc-completed&post_type=shop_order">Hide completed orders</a>');
	return $views;
}

add_action( 'load-edit.php', 'wc_filter_completed' );
function wc_filter_completed() {
	global $typenow;
	if( 'shop_order' == $typenow ) {
		add_filter( 'posts_where' , 'posts_where_filter_completed' );
	}
}

function posts_where_filter_completed( $where ) {
	global $wpdb;       
	if ( is_admin() && isset( $_GET[ 'exclude_order_status' ] ) && !empty( $_GET[ 'exclude_order_status' ] ) ) {
		$status = $_GET[ 'exclude_order_status' ];
		$where .= " AND $wpdb->posts.post_status != '$status'";
	}
	return $where;
}
