You should be able to install Windows 10 cleanly from a USB drive.
I prefer using a USB drive to install my operating systems, but you can install it from your PC simply by clicking the white windows icon in the bottom right of your taskbar and clicking "Upgrade Now".
To have a safer time using Windows 10, go into Cortana and search "Privacy" - Then go into the settings and turn EVERYTHING off. Go into every single category and you shouldn't see anything ticked green. Everything should be off.
Also, in Cortana, click "Stop Getting to Know Me" - It's part of the privacy settings.
Once you've turned everything off including "get to know me (cortana)" in your privacy settings, I'd suggest that you install the following freeware - it will secure your Windows 10 experience.
Once installed, open it up with administrative privileges and click "Immunize". Also, go into "Optional" and apply blocks to everything there too.
Once you're immunized with Spybot Anti-Beacon and turned off everything in privacy settings, you're good to go!
Edited by DanieI, 17 May 2016 - 04:45 PM.