title: Permission error with moviepy
body: <p>I am trying to convert an mp4 video into an mp3 audio using moviepy then delete the video, the code is as follows:</p>
  
  <pre><code>import moviepy.editor as mp
  #converting mp4 to mp3
  clip = mp.VideoFileClip("videos/test.mp4")
  clip.audio.write_audiofile("test.mp3")
  del clip
  
  #delete video file after converting
  os.remove("videos/test.mp4")
  print("Video Deleted")
  </code></pre>
  
  <p>This gives the following error PermissionError: [WinError 32] The process cannot access the file because it is being used by another process.</p>
  
  <p>I know I should close the process on the mp4 file in order to close it such as doing with files but isn't <code>del clip</code> responsible for that ?</p>