注意：根据后来的反馈和对您问题的更新，您似乎正在寻找下面的用例2。

用例一：如果$folderPath的子文件夹中只有个文件**（且没有自己的子文件夹）：

$folderPath = "E:\Data\Report"
$limit = (Get-Date).AddDays(-30)

Get-ChildItem -LiteralPath $folderPath -Directory | 
  ForEach-Object {
    # Determine which files inside the folder at hand should be deleted, 
    # and which should be kept.
    $toDelete, $toKeep = 
      ($_ | Get-ChildItem -File -Force).
      Where({ $_.LastWriteTime -lt $limit }, 'Split')
    # No files to keep? Delete the folder at hand as a whole.
    if (-not $toKeep) { 
      $_ | Remove-Item -Recurse -Force -WhatIf
    } 
    # Should a subset of the files be deleted?
    elseif ($toDelete) {
      $toDelete | Remove-Item -Force -WhatIf
    }
    # Otherwise: no files to delete.
  }

注意：上面命令中的-WhatIf公共参数 * 预览 * 操作。删除-WhatIf，并在确定该操作将按您的要求执行后重新执行。

用例二：如果文件太旧，且子文件夹为空，则必须从每个子文件夹的整个子树中删除。

注意事项：

• 为了安全起见，-WhatIf在下面的第一个Remove-Item调用中保留了下来。但是，这意味着解决方案的 folder-deletion方面不能预览，因为只有在文件和子文件夹实际被删除时，逻辑才会启动。换句话说：你只能预览哪些 * 文件 * 将被删除。
• 通过在folder-deletion Remove-Item调用中 not 使用-WhatIf，任何 * 已经为空 * 的子目录将立即被删除。

$folderPath = "E:\Data\Report"
$limit = (Get-Date).AddDays(-30)

Get-ChildItem -LiteralPath $folderPath -Directory | 
  ForEach-Object {

    # Step 1: In the entire *subtree* of the subfolder at hand,
    #         delete all too-old files.
    $_ | Get-ChildItem -Recurse -File -Force | 
        Where-Object LastWriteTime -lt $limit |
        Remove-Item -Force -WhatIf

    # Step 2: Examine all folders in the subtree, including the subfolder at hand,
    #         starting at the lowest level, 
    #         and iteratively delete any (now) empty folders.
    & { $_; $_ | Get-ChildItem -Recurse -Directory -Force } |
        Sort-Object -Descending { ($_.FullName -split '[\\/]').Count } |
        ForEach-Object {
          # Is this folder (now) empty?
          if (-not ($_ | Get-ChildItem -Force | Select-Object -First 1)) {
            $_ | Remove-Item # Remove this folder
          }
        }
  }