Yes, as above, run through the RESET option & you'll have a clean factory install with your drivers. All activators/crap gone!
Not a big deal to backup and save all installed Drivers from the running old Windows! I'd did that on my own Windows Tabs ( have 3 of them) and used them for to change from Home to Pro on that Tabs with no any problems. That also was required a new and clean install of Windows 10Pro, now on 1809 build 17763.316.
Where can one obtain the latest clean copy of Microsoft Toolkit? Need to activate Windows 10 and Office 2016.
If he bought a genuine Product Key (see Post #3) there isn't any need to use any KMS or pirate way! All he has to do is to add an ei.cfg and pd.txt file to the Sources Folder of the ISO of Win 10 Pro and there shouldn't be any problem. The BIOS of his Tablet would have a Home Key embedded and therefore that correct ei.cfg file is needed. And if he put his genuine Product Key into the pd.txt file, windows should bypass the embedded BIOS info and fully activate the Tablet with a new HWID. That said, it will work only if the used new Product Key is really genuine and unused. Upfront he could check the new Product Key with the VAMT tool to download free of charge from MS Website. The use of that KMS Activation with none genuine KeyManagementServices is still illegal. If the user has valid legal access to any KMS Server, he could use that service with no legal problems. But using KMS will not create a HWID usable with MS Activation System!