My buyer doesn’t reply me with more time, after that the order become complete, and message me in inbox so, him needs a different logo design for new company instead of the first logo design, and I designed it, now him needs to cancel order.
A buyer cannot cancel his order unless you agree to his cancellation request. If you don’t want to give him your work for free, don’t accept his cancellation request.
The buyer say me in inbox to cancel the order, and I don’t know to cancel because the order is completed
Why would you cancel a completed order? You already did the work that you were hired to do. You did it, you delivered it, now you are entitled to be paid for that work.
Communicate with your buyer a little more. Inquire if he’s dissatisfied with the finished product, do you offer revision(s)? If so, let the buyer know it’s readily available. Don’t be so hasty to click on the cancel button. The buyer requesting to cancel without a logical reason is just unreasonable.
If I remember correctly, it’s no longer possible to cancel completed orders. Only Customer Support can do that.