What version of W10 did you have prior to the AU update today? Also, please check the version that's on your computer now after the 9.18.2016 update from this morning. Here's how to check your W10 version; read this link:
Widen date/time area in taskbar system tray.
It's anti-W10 to remove your password, and poses a security risk as you are no doubt aware. It's possible that W10 refuses to allow this in the most current AU update. I've read recently that they are removing that capability or have already done so since the W10 Aug. 2nd update (AU). I would re-check that login password box, reboot your computer and try it again. If you are then able to get to your W10 desktop from the previous version, that fixes your problem.
Microsoft has removed other features completely from W10 without really telling the public, such as the Missing DVD player app and the Windows Movie Maker. So, this would not be a big surprise.
I had the newest AU update come into my laptop yesterday morning,
v1607 OS build 14393.187, which is the latest, and it developed a very bad problem with about 15 keys on my keyboard not working correctly (alpha + numeric). Had to completely uninstall the AU from the laptop to get it working again.
Post back the 2-W10 version numbers from your computer (before and after the Update), and we can perhaps advise you further.
Thanks,
<<<BIGBEARJEDI>>>