Clean installing and removing bloatware is actually easier in Windows 10. Simply upgrade the machine, go to settings --> reset --> wipe entire drive (or whatever its called), then wait. Windows creates a bloat free image made from the system files and removes anything preinstalled.
This is unfortunately not always true. I've had HP devices with bloatware included in the recovery partition, which Windows uses to do the reset.
I don't know how other manufacturers configure the recovery partition, but it's pretty easy for OEMs to stuff whatever they want in there.
The only way to be 100% guaranteed bloatware free is a clean install from an MS ISO.
OP:
After your initial upgrade to W10, you no longer require a serial key to do a clean install. MS stores the hardware signature of your machine and the associated W10 license key in the cloud.