Developer forum

It depends if the checkout handler supports it. Here is a bit of code from the payments web api you can probably use.

var orderService = new OrderService();
                orderService.MarkOrderAsDeleted(order);
                var manager = OrderManager.GetFor(order);
                if (manager.IsOperationSupported(OrderOperations.Cancel))
                {
                    if (order.CaptureInfo.State != OrderCaptureInfo.OrderCaptureState.Success)
                    {
                        TryCancel(result, manager);
                    }
                    else
                    {
                        var availableToReturn = 0.0;
                        if (OrderReturnInfo.CheckIfOrderReturned(order, ref availableToReturn))
                        {
                            TryCancel(result, manager);
                        }
                        else
                        {
                            result.Status = "Success";
                            result.Message = "The order has been captured, you need to process a refund first.";
                        }
                    }
                }
                else
                {
                    result.Status = "Failed";
                    result.Message = "Cancel operation is not supported for specified order";
                }

private void TryCancel(PaymentOperationResultModel result, OrderManager manager)
        {
            try
            {
                if (manager.CancelOrder())
                {
                    result.Status = "Success";
                    result.Message = "Order has been canceled successfully.";
                }
                else
                {
                    result.Status = "Failed.";
                    result.Message = "Order has not been canceled.";
                }
            }
            catch (Exception e)
            {
                result.Status = "Failed";
                result.Message = $"Unhandled internal exception: {e.Message}";
            }
        }