How to create a new account/user on windows 10 that doesn t have file from the administrator account?

Go to settings>Accounts>familyand other users

Choose other user then I don;t have their sign in then add without a microsoft account and it will default to a local account which you can upgrade to an administrator if you want.

doesn't have what file?

to make a new account, just open Settings, Users, and make a new one there.

you can delete anything you don't want.

I've created the secondary account from my old registration on Microsoft Forums (now Microsoft Communities). It was enough to use e-mail address which I've used there as well as the password (not for the e-mail but for Microsoft Forums). There was no user files there.