From Evernote:

Reset all local admin ID's on all servers in hosts file

$Server=(Read-Host "Server")
$UserName=(Read-Host "UserName")    
$Password = Read-Host -assecurestring "Please enter your password"
$PasswordConfirm = Read-Host -assecurestring "Confirm password"
$IsPasswordGood = [string]::Compare($Password, $PasswordConfirm, $IsPasswordGood)
$tempCredential = New-Object System.Management.Automation.PsCredential "None",$password
    
If ($IsPasswordGood -eq 0)
     {
     $Password = $tempCredential.GetNetworkCredential().Password
     $LocalUser =[adsi]("WinNT://$Server/$Username, user")
     $LocalUser.psbase.invoke("SetPassword", $Password)
     }
     Else
     {
     Write-Host "** Passwords don't match **"
     }