Sitecore PowerShell Script to delete unused items in the Media Library

$mediaLibraryRootPath = "master:/sitecore/media library"

# HasReference determines if the specified item is referenced by any other item.
function HasReference {
    param(
        $Item
    )

    $linkDb = [Sitecore.Globals]::LinkDatabase
    $linkDb.GetReferrerCount($Item) -gt 0
}

# Get-MediaItemWithNoReference gets all the items in the media library and checks if they have references. If the item has no reference, the media item is saved locally and then deleted.
function Get-MediaItemWithNoReference {

    $items = Get-ChildItem -Path $mediaLibraryRootPath -Recurse | 
        Where-Object { $_.TemplateID -ne [Sitecore.TemplateIDs]::MediaFolder }

    $i = 0
    foreach($item in $items) {
        if(!(HasReference($item))) {
            $i = $i + 1
            Write-Output "$($i). $($item.ItemPath)"
            $item | Remove-Item 
        }
    }
}

# Run the script.
Write-Output "Items to delete:"
Get-MediaItemWithNoReference