You want the Remove-UserOwnership cmdlet.
Provided the CSV contains the following fields
"VM","User"
"VM1","user1"
"VM1","user1"
You can do something like this
Import-Csvinput.csv-UseCulture|%{ $vm=Get-DesktopVM-Name$_.VM
if($vm.user_displayname-eq$_.User){ Remove-UserOwnership-machine_id$vm.machine_id
} }