Magento - How to enable cancel button for a processing order (invoice created)

Question

I have some orders in Processing state. I know Magento do not allow to cancel invoiced orders, just create a credit memo, but I need to change it. I need to do something to undo the creation of the invoice and return it to "pending", or just cancel it.

Answer 1

Any invoiced orders in Magento cannot be canceled, but they can be closed.

You need to issue a credit memo, which is refund in Magento.