If you need to manually change an Order Status or Cancel an order, whether it is one that you created or one that auto generated, you can do so in the Order.
Navigate to Order
Navigate to the Order you need to update.
Edit Order Status
Once you are in the order, select the gray pencil on the left near the order number.
The Edit Order Status box will pop up with the current status shown.
You can manually change this status by clicking on the drop down menu to choose an alternative status.
You can also remove or change any tags if necessary.
Once you have updated to your desired status/tag, click Save.