Well you may have to install Windows 8 first since I think it has to be installed for the upgrade. As long as its not enterprise. Since you cant upgrade from enterprise
Windows 10 so I've read you will be able to create an ISO with it after (you have to extract an ESD file) to create it
Then you can use something like
rufus to extract it to a flash drive. Then you can boot from it
If you want to do a clean install of Win10