This message was posted on behalf of Intel Corporation
Thank you for joining the Intel® NUC Community. I am sorry to hear you are having issues with this matter.
If by mistake the Windows® 10 partition and the recovery partition from was deleted then unfortunately, there is no way to get the product key back. Microsoft® policy does not allow us to send a product key. You could get a Windows® 10 image and reinstall the operating system, or you can get in touch with Contact Support and check the replacement options for the unit.