It seems that #chntpw still works for #Windows10. But it can only clear / reset the password of an existing user. It cannot set a password or create a new user.

Update:
I have seen that Grzegorz Tworek created a proof of concept #OfflineSAM to change the #SAM database:
https://github.com/gtworek/PSBits/tree/master/OfflineSAM