A few of you sent mail asking how to delete an agent using the Command Shell. There is a Cmdlet for uninstalling an agent called Uninstall-Agent. However, uninstalling an agent will not work if the computer the agent is hosted by is not available. To help address the issue I created a function to automate the process. Keep in mind this function should only be used to delete an agent hosted by a computer that no longer exists otherwise you should use Uninstall-Agent. 

# Summary
#     Delete an agent hosted by a non-existent computer.
# Params
#     AgentNames - An array of strings that contain the FQDN of agents to delete.
# Returns
#     None
function global:Delete-Agent([System.String[]] $agentNames)
{
 $NoAgentsErrorMsg = "`nNo agent names specified. Please specify the FQDN for each agent you want to delete.`n";

 if ($agentNames -eq $null)
 {
  Write-Host $NoAgentsErrorMsg;
  return;
 }

 $administration = (get-item .).ManagementGroup.GetAdministration();

 $agentManagedComputerType = [Microsoft.EnterpriseManagement.Administration.AgentManagedComputer];

 $genericListType = [System.Collections.Generic.List``1]
 $genericList = $genericListType.MakeGenericType($agentManagedComputerType)

 $agentList = new-object $genericList.FullName

 foreach ($agentName in $agentNames)
 {
  $agent = Get-Agent | where {$_.PrincipalName -eq $agentName}
  
  if ($agent -eq $null)
  {
   $msg =  "Agent '{0}' not found." -f $agentName;  
   Write-Host $msg;

  }
  else
  {
   $agentList.Add($agent);
  } 
 }

 if ($agentList.Count -eq 0)
 {
  Write-Host $NoAgentsErrorMsg;
  return;
 }

 $genericReadOnlyCollectionType = [System.Collections.ObjectModel.ReadOnlyCollection``1]
 $genericReadOnlyCollection = $genericReadOnlyCollectionType.MakeGenericType($agentManagedComputerType)

 $agentReadOnlyCollection = new-object $genericReadOnlyCollection.FullName @(,$agentList);

 $msg = "`nDeleting {0} agents:`n" -f $agentReadOnlyCollection.Count;
 Write-Host $msg;
 foreach ($agent in $agentReadOnlyCollection)
 {
  Write-Host $agent.PrincipalName;
 }
 
 $administration.DeleteAgentManagedComputers($agentReadOnlyCollection);
}
 

Hope that helps and as always please post your questions and comments and I will make sure they are addressed in future posts.

Roger Sprague