Start-Sleep 1
C:\Windows\System32\net.exe user Marek /active:no
$session_id = ((C:\Windows\System32\quser.exe | Where-Object {$_ -match 'Marek' }) -split ' +')[2]
If ($session_id) {
    logoff $session_id
    Start-Sleep 1
    shutdown /s /f /t 0
}