SharePoint Online: Delete All Unique Permissions from a Site Collection using PowerShell

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"
 
#Function to Delete Unique Permission from a Web and its content
Function Reset-SPOUniquePermission([Microsoft.SharePoint.Client.Web]$Web)
{
    Write-host -f Magenta "`nSearching Unique Permissions on the Site:"$web.Url
    
    #Check if the given site is using unique permissions
    $Web.Retrieve("HasUniqueRoleAssignments")
    $Ctx.ExecuteQuery()
    
    #Get the Root Web
    $RootWeb = $ctx.site.RootWeb
    $Ctx.Load($RootWeb)
    $Ctx.ExecuteQuery()

    ### Reset broken inheritance on the Web
    If($Web.HasUniqueRoleAssignments -and $Web.ID -ne $RootWeb.ID)
    {
        #powershell to delete unique permissions of a subsite in sharepoint online
        $Web.ResetRoleInheritance()
        $Web.Update()
        $Ctx.ExecuteQuery()    
        Write-host -f Green "`t Unique Permissions Removed from the Site: $SiteURL!"
    }
        
    ### Reset unique permission in Lists
    Write-host -f Magenta "`t Searching Unique Permissions on the Lists"
    $Lists =  $Web.Lists
    $Ctx.Load($Lists)
    $Ctx.ExecuteQuery()

    #Exclude system lists
    $ExcludedLists = @("App Packages","appdata","appfiles","Apps in Testing","Cache Profiles","Composed Looks","Content and Structure Reports","Content type publishing error log","Converted Forms",
     "Device Channels","Form Templates","fpdatasources","Get started with Apps for Office and SharePoint","List Template Gallery", "Long Running Operation Status","Maintenance Log Library", "Style Library",
     ,"Master Docs","Master Page Gallery","MicroFeed","NintexFormXml","Quick Deploy Items","Relationships List","Reusable Content","Search Config List", "Solution Gallery", "Site Collection Images",
     "Suggested Content Browser Locations","TaxonomyHiddenList","User Information List","Web Part Gallery","wfpub","wfsvc","Workflow History","Workflow Tasks", "Preservation Hold Library")
    
    #Iterate through each list
    ForEach($List in $Lists)
    {
        $Ctx.Load($List)
        $Ctx.ExecuteQuery()

        If($ExcludedLists -NotContains $List.Title -and $List.Hidden -eq $false)
        {
            #Check if the given site is using unique permissions
            $List.Retrieve("HasUniqueRoleAssignments")
            $Ctx.ExecuteQuery()
 
            #Reset broken inheritance of the list
            If($List.HasUniqueRoleAssignments)
            {
                #delete unique permissions of a subsite in sharepoint online powershell
                $List.ResetRoleInheritance()
                $List.Update()
                $Ctx.ExecuteQuery()    
                Write-host -f Green "`t`tUnique Permissions Removed from the List: '$($List.Title)'"
            }

            Write-host -f Magenta "`t`t Searching Unique Permissions on the Lists Items of '$($List.Title)'"

            #Query to batch process
            $Query = New-Object Microsoft.SharePoint.Client.CamlQuery
            $Query.ViewXml = "<View Scope='RecursiveAll'><RowLimit>2000</RowLimit></View>"

            ### Reset unique permission on List items
            Do {  
                #Get all items from the list - in batches
                $ListItems = $List.GetItems($Query)
                $Ctx.Load($ListItems)
                $Ctx.ExecuteQuery()
           
                $Query.ListItemCollectionPosition = $ListItems.ListItemCollectionPosition
  
                #Loop through each List item
                ForEach($ListItem in $ListItems)
                {
                    $ListItem.Retrieve("HasUniqueRoleAssignments")
                    $Ctx.ExecuteQuery()
                    if ($ListItem.HasUniqueRoleAssignments -eq $true)
                    {
                        #Reset Permission Inheritance
                        $ListItem.ResetRoleInheritance()
                        Write-host  -ForegroundColor Green "`t`t`t Unique Permissions Removed and Inheritence Restored on Item ID:" $ListItem.ID
                    }
                }
                $Ctx.ExecuteQuery()
            } While ($Query.ListItemCollectionPosition -ne $null)
        }
    }

    #Process each subsite in the site
    $Subsites = $Web.Webs
    $Ctx.Load($Subsites)
    $Ctx.ExecuteQuery()        
    Foreach ($SubSite in $Subsites)
    {
        #Call the function Recursively
        Reset-SPOUniquePermission($Subsite)
    }
}

#Config Parameters
$SiteURL= "https://crescent.sharepoint.com/sites/marketing"
 
#Get Credentials to connect
$Cred = Get-Credential
 
Try {
    #Setup the context
    $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
    $Ctx.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.UserName,$Cred.Password)
     
    #Get the Web
    $Web = $Ctx.Web
    $Ctx.Load($Web)
    $Ctx.ExecuteQuery()
    
    #Call the function to delete unique permission from all sites in the site collection
    Reset-SPOUniquePermission $Web
}
Catch {
    write-host -f Red "Error:" $_.Exception.Message
}