This is a step by step guide of doing a clean install of windows 10 as of September 2017. If you are reading this 6 months on things may have changed slightly.
1. The first thing you will need to do is boot your computer from the Windows install USB you have created (click here if you have not created a Windows install USB). To boot from USB insert the USB stick in to a spare port then turn on your computer then immediately keep tapping the boot option key. Boot option keys vary from device to device common boot option keys which are found at the top of the keyboard are ESC, F8, F9, F12. If you fail at first to get the boot menu hold down the power button until the computer turns off and try again.
2. The first menu after booting from the USB will ask you to select a your preferred language. Select your language by using the drop down menus and clicking on the relevant one then click "next".
3. Click on "Install Now"
4. If you don't have a product key which you probably don't then click on "I don't have a product key"
5. Click on the version of windows you have then click "next". If you don't know which version you have it can be found on the sticker with the windows logo some where on your computer.
6. Click the checkbox "I accept the license terms" then click "next"
7. Click on "custom: install Windows only (advanced)"
8. Click on each drive not labelled "Unallocated space" then click "delete" repeat until only one drive remains. Next click "New" then click "Apply"
9. Click "OK"
10. Click "Next"
11. Grab a cup of tea while windows installs. Your computer will reboot several times.
12. Click on the correct region if wrong then click "Yes".
13. Click "Yes"
14. Click "Skip"
15. Click "Offline account"
16. Click "No"
17. Enter your name then click "Next"
18. Create a password and enter it into the box then click "Next"
19. Re-enter the password from the previous step then click "Next"
20. Enter a password hint, I suggest not putting a real hint for security. Click "Next"
21. Click "No".
22. Click on each of the sliders to turn off all the options then click "Accept". This is the final step. After a few minuets you will be greeted with your desktop.