You dont have to do all this.
for win 7 :
download and install wincdemu
download win 10 iso
mount win 10 iso using wincdemu and run setup
setup will ask you what to keep....choose nothing
and you have a fresh win 10 installation
for win 8/8.1
download win 10 iso
open iso
run setup
choose nothing to keep
PS: you can choose to keep personal files only...and it will remove all programs and settings