title: How do I clean a blob before copying to it (Azure release pipeline)
body: <p>My release pipeline uploads to blob storage using 
  <a href="https://docs.microsoft.com/en-us/azure/devops/pipelines/tasks/deploy/azure-file-copy?view=azure-devops" rel="nofollow noreferrer">Azure File Copy</a></p>
  
  <p>I want to delete the existing files in the blob before copying over the new files.</p>
  
  <p>The help shows that</p>
  
  <pre><code>cleanTargetBeforeCopy: false
  </code></pre>
  
  <p>only applies to a VM</p>
  
  <p>(since it is a release pipeline I can't edit the YAML anyway)</p>
  
  <p>The tool tip for Optional Arguments shows</p>
  
  <blockquote>
    <p>Optional AzCopy.exe arguments that will be applied when uploading to
    blob like, /NC:10. If no optional arguments are specified here, the
    following optional arguments will be added by default. /Y,
    /SetContentType, /Z, /V, /S (only if container name is not $root),
    /BlobType:page (only if specified storage account is a premium
    account). If source path is a file, /Pattern will always be added
    irrespective of whether or not you have specified optional arguments.</p>
  </blockquote>