One option is to buy a "clean" computer, but they come with a premium price.
Another is the following:
* do the initial out-of-the-box install of Windows 10
* download a fresh image to a flashdrive from here:
https://www.microsoft.com/en-ca/software-download/windows10
* reinstall Windows from the flashdrive
That purges most of the pre-installed junk.
Follow that with a perusal of Setting > Apps & delete anything unwanted like Xbox.
Would recommend that a tech-savvy friend help you.
Buenchico mentioned good alternatives for MS Office.