Resetting and upgrading windows on a former work-laptop

Darkium

Prominent
Jun 4, 2017
2
0
510
Hi!

I recently got a laptop that had previously been used by a company. It has windows 8 installed, but also a bit of bloatware and, most importantly, a UAC system from the company.
I'd like to do two things, but am not sure how to do so exactly.
1. Reset windows completely: Remove the UAC, the bloatware, EVERYTHING, in order to have a completely blank windows installation - However, it should be one that is still "legit". On one of my previous pc's I once simply wiped the whole disk, but ended up installing a not-so-legit windows version because I did not have a CD to reinstall the old, legit version.
Basically, I'm not a 100% sure how to wipe everything while keeping my windows legal and activated.
2. Upgrade from win8 to win10, even though the period has already expired. (Windows8 is an absolute abomination.)

And that's pretty much it. I'd really appreciate a few tips!
Thanks a lot.