I don't know if this is suggested or not

I wanna suggest some button right under “Cancel Order”, something like “Mark As Done” so we can mark the order as delivered, it would be useful, can I add it? or it should be by developers?

You can add anything you want. Can you explain more of why you want this button maybe we can help you design something specific for your needs.

I want to keep track of the orders, for example I have 10 orders, I can click and change the color of the selected order to be “DONE”

Check this out.