Angels have the Phone Box
I just did one yesterday (on a borked forced-upgrade+revert). Booted to the W10 USB, chose custom installation, had it delete all partitions it would let me delete, then selected to format the partition with the OS on it and install.
Here's the tut:
Windows 10 - Clean Install - Windows 10 Forums
Finished with a clean, 3-partition install (this one was an upgrade from W8>W8.1>W10 and had like 6 or 7 partitions on it, including the OEM recovery, which is useless), and it is running smoothly.
I'm really sorry we couldn't get this resolved. I am sure the Norton has something to do with it. If it were me, I would use Defender + the paid version of Malwarebytes Antimalware, (for active protection), then add the Malwarebytes Antiexploit free; round it out with the free version of SuperAntiSpyware (manual updates and scans).
Good luck and let us know how it goes.