title: Not able to delete files using conda clean --all
body: <blockquote>
  <p>(you may need to reboot to free file handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\keyring.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\logged_subprocess.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\makedirs.py.  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\metaclass.py.  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\notebook_analyzer.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\pip_api.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\plugins.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\py2_compat.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\rename.py.  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\simple_status.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\slugify.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\streaming_popen.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\toposort.py.  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\windows_cmdline.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal\ziputils.py.  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\internal_<em>init</em>_.py.  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\test\test_conda_env.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\test\test_download_provider.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\test\test_redis_provider.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\test_<em>init</em>_.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\conda_env.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\download.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers\redis.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\providers_<em>init</em>_.py.
  Please remove this file manually (you may need to reboot to free file
  handles) WARNING
  conda.gateways.disk.delete:unlink_or_rename_to_trash(143): Could not
  remove or rename
  C:\ProgramData\Anaconda3\pkgs\anaconda-project-0.10.1-pyhd3eb1b0_0\site-packages\anaconda_project\requirements_registry\requirements\test\test_conda_env.py.
  Please remove this file manually (you may need to reboot to free file
  handles)</p>
  </blockquote>