An online money transfer can only be cancelled if it has not been paid out to the receiver in the destination country. You can cancel the transfer if its status is not shown as CANCELED or DELIVERED online. You can check the status of your transfer here.
Note that you can get a full refund if you cancelled the transfer before it’s paid out to the receiver.
You can check your transfer status online. All you need is the sender’s or receiver’s name and the tracking number (MTCN) printed on the receipt.