Revoke RDS CAL from powershell or and command

I am trying to use powershell to query all the LicenseID  and the ones that come up as unknown send a revoke command.

I have everything ready up to the revoke part. i cannot find a revoke command .  i saw this on a site but now sure how to implement it :

Win32_TSIssuedLicense:

Windows Server 2008 has a WMI class named "Win32_TSIssuedLicense" for managing issued per device CALs. This WMI class provides the following interface to manually revoke issued CALs:

Revoke: This API can be used to manually revoke an issued CAL. This is a not a static function.

The syntax of the API is

uint32 Revoke(

[out] uint32 RevokableCals,

[out] DATETIME NextRevokeAllowedOn );