((gwmi win32_useraccount | ? { $_.localaccount})[0]).sid | `
% {$_.substring(0, $_.lastindexof("-"))}
或：
gwmi win32_useraccount |`
? { $_.localaccount } |`
Select-Object -First 1 |`
Select-Object sid |`
% {$_.sid.substring(0, $_.sid.lastindexof("-"))}