Enable auto sign-in on Windows 10

ok, if you make the following modification to your registry the option will be available again in netplwiz. Default setting is 2.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\PasswordLess\Device]
"DevicePasswordLessBuildVersion"=dword:00000000

0 = on
2 = off

It was because my VM was part of a domain (an organization in Windows 10 parlance). Removing the machine from the domain ("disconnecting from the organization") made the checkbox reappear and allowed me to enable auto-login.

You can use Autologon.exe (Sysinternals tool) or using registry keys:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
"AutoAdminLogon"="1"
"DefaultDomainName"="DOMAINNAME"
"DefaultUserName"="USERNAME"
"DefaultPassword"="PASSWORD"

Extracted from: http://www.sysadmit.com/2016/01/windows-configurar-autologin.html