how can I make windows 10 not boot?

Smash the hard drive with a sledgehammer.

I'm doing this for my son to troubleshoot he is in tech school

Well, think of it like a math problem. You don't just write a bunch of numbers down and say "do math."  If my kid wad learning addition, I'd make a sheet of addition problems for him to solve. Writing out multiplication tables wouldn't help him much

You don't want to just randomly make windows "not boot" and then say "go. Troubleshoot."  There are way too many unknowns. You need to have a *specific* goal in mind.

And like teaching any skill, you have to have some of the knowledge yourself to teach it. Otherwise it is best left to the school that he is enrolled in.

You can delete the registry hives, shut down, and the computer will never work again, forcing a bare metal installation of Windows.

Is that what you are trying to accomplish?

Thank you Malmensa, this is what I needed and what I asked for.

Excellent thanks