If there is an item in your cart that you want to delete at any time just press the minus symbol next to it. What do you mean when you say you “cancelled one”?
If you pressed ‘Pay’ with both items in the cart but didn’t pay the full amount shown then the order will show as unpaid or underpaid. It should auto cancel in due course with your funds returned and you can start again. If this doesn’t happen, contact transaxe 👍