Ah, I see it's been deprecated in Win 10. Ignore my last post.
How do you create a custom image like you could do with recimg in Win 8.1?
Edit: I just found out I don't have Winre.wim in this folder c:\windows\system32\recovery. That seems to be why Windows RE is not and cannot be, enabled.
REAGENTC.EXE: The Windows RE image was not found.