Remove RDS 2016 CALS from the license server

Remove An Individual RDS CAL License Pack Using Powershell (User or Device CAL)

• Open PowerShell elevated as an administrator
• Type the following command to list the RDS Licenses to find the KeyPackID 

Get-WmiObject Win32_TSLicenseKeyPack

• Run the below command to remove the licenses pack from your RD Server

wmic /namespace:\\root\CIMV2 PATH Win32_TSLicenseKeyPack CALL UninstallLicenseKeyPackWithId X

Where “X” is the value of KeyPackId

P.S: Please be aware, you will need to re-install the License if you want to use it again.