#Remove files older than...
Get-ChildItem -File -Recurse | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-180) } | Remove-Item -Force

#Remove empty folders (may be repeated up to X times...)
Get-ChildItem -Directory -Recurse | Where-Object { -not (Get-ChildItem -Path $_.FullName -Recurse -Force -ErrorAction SilentlyContinue) } | Remove-Item -Force