DeleteMachinesByEnvName.ps1

$apiKey = "Your API Key"
$OctopusURL = "Your Octopus URL"
 
$Header =  @{ "X-Octopus-ApiKey" = $apiKey }
 
#Getting all machines given an Environment name
$EnvironmentName = Read-Host 'What environment do you want to wipe out?'
Write-Warning "You are about to remove ALL machines from the $EnvironmentName environment."
$confirm = Read-Host 'Are you sure you want to continue? Y/N'

if($confirm = 'Y'){
    $Environment = Invoke-WebRequest -Uri "$OctopusURL/api/Environments/all" -Headers $Header| ConvertFrom-Json
 
    $Environment = $Environment | ?{$_.name -eq $EnvironmentName}
 
    $Machines = (Invoke-WebRequest -Uri "$OctopusURL/api/Environments/$($Environment.id)/machines" -Headers $Header| ConvertFrom-Json).items
 
    #Deleting all machines found on the environment
    $total = $Machines.Count
    for ($i=0; $i -lt $Machines.Count; $i++){
        $percentComplete = (($i/$total)*100)
        Write-Progress -activity "Deleting Machines in the $EnvironmentName environment." -percentComplete $percentComplete -currentOperation "Deleting $($($Machines[$i]).Name).                 [$percentComplete %] Complete."
        #Running a DELETE agains the machine link will delete it from Octopus
        Invoke-WebRequest "$OctopusURL$($($Machines[$i]).Links.Self)" -Headers $Header -Method Delete | Out-Null
    }
    Write-Host "Finished deleting $total machines from the $EnvironmentName environment." -f Green
}