To access local user accounts and assign a new password, you can use the low-level WinNT: namespace.
Note: you do need Administrator privileges to assign new passwords.
This script would assign a new password for the local Administrator account:
#requires -Version 1 $Password = 'P@ssw0rd' $admin = [adsi]("WinNT://$env:computername/administrator, user") $admin.psbase.invoke('SetPassword', $Password)