title: Cannot remove submodule from Git repo
body: <p>I have a subproject in a Git repo that I want to remove but am not able to. On the GitHub web interface the submodules are shown with black (or grey) folder icons and are not clickable. </p>
  
  <p><img src="https://i.stack.imgur.com/iL8FO.png" alt="submodule in git repo"></p>
  
  <p>There are some issues with that folder that even if my local code has files in that folder and I push to my repository, changes are not applied on the GitHub remote. Somehow this folder is ignored. I checked that it is not in <code>.gitignore</code> file.</p>
  
  <p>On trying to remove the subproject I used:</p>
  
  <pre><code>git submodule deinit submodule-name
  </code></pre>
  
  <p>but it gives error that </p>
  
  <blockquote>
    <p>error: pathspec 'submodule-name' did not match any file(s) known to git.
    Did you forget to 'git add'?</p>
  </blockquote>
  
  <p>What's the issue here?</p>