Unable to delete orphaned VMs by using Powershell from catalog which has already been removed via Powershell.

When running command: Remove-ProvScheme
The below error is seen:
"Leaving the non-persistent virtual machines of the provisioning scheme 'provisioning scheme name' at the hypervisor is not allowed.

1. Remove the left over VMs that are still associated with the Prov-scheme. 
   • To check what VM's are left, you will need to run command: Get-ProvVM -ProvisioningSchemeName 'provisioning scheme name' | Select-Object vmname
2. Once you have the name of the VMs, run the commands below: 
   • Get-ProvVM -VMName "Name of VM"
     • Note: from the output, you will need to take note of the ProvisioningSchemeUID field and copy the UID. 
   •  Unlock-ProvVM -ProvisioningSchemeUID "UID taken from running output of running the previous command"
   •  Get-ProvVM -ProvisioningSchemeUID ""UID taken from running output of running the previous command" | Remove-ProvVM -VMName "Name of VM"
3. Once you do this for each of the VMs, you will then be able to remove the prov-scheme by running command: 
   • Remove-ProvScheme -ProvisioningSchemeName 'provisioning scheme name'

Problem Cause

• https://developer-docs.citrix.com/en-us/citrix-virtual-apps-desktops-sdk/current-release/MachineCreation/Get-ProvVM.html
• https://developer-docs.citrix.com/en-us/citrix-virtual-apps-desktops-sdk/current-release/MachineCreation/Unlock-ProvVM.html
• https://developer-docs.citrix.com/en-us/citrix-virtual-apps-desktops-sdk/current-release/MachineCreation/Remove-ProvScheme.html