Delete associated workflows across site collection level

<#
******-----------------------------------------------------------------------******
Author          -> Shiv Mangal Singh
Date            -> 8th Feb - 2017
Description     -> This Script will delete all Associated Workflows across site collection level from lists & document libraries.

Site Collection Name --> "https://ms.contoso.net/global/contososs"

******-----------------------------------------------------------------------******
 #>

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue
# get site collection name
$Site = Get-SPSite "https://msd.contoso.net/sites/test"

# loop through All subsites at Site Collection Level
foreach($Web in $Site.AllWebs)
{
  # Loop through all lists at sites level
  foreach($list in $Web.Lists)
  {
 
    # Check Associtaed Workflow through all sub sites
    foreach($Wf in $list.WorkflowAssociations)
    {
     Write-Host $wf.id
     # Checking the workflow in list
     if($Wf -ne "")
     {
     # Removing the workflow across Site collection level from lists & document library
      $list.WorkflowAssociations.Remove($wf.id)
      $list.update()
     }
    }

  }
}