Use the Windows 10 media creation tool. That will create installation media on a USB memory stick and you can clean install from there. Since you already upgraded to Windows 10 and I assume it was activated, it will auto activate again. As before, you will have to download the appropriate drivers.
However, did your system originally come with Windows 10 installed from the factory? If so you can also download the Dell factory image recovery and put the system back to the way it was from the factory.
...did your system originally come with Windows 10 installed from the factory?
No, sadly it did not.
My plan is to reset to Windows 7 factory using the internal reset, so that I get all the default drivers. Then re-upgrade and hope that it works this time.