title: Apps Script - Remove a Protection
body: <p>I want to restrict cell editing in a Google Sheet by only allowing a user to edit empty cells or cells filled by him, but not cells filled by other editors. Put simply :</p>
  
  <ol>
  <li>If a cell is blank, any document editor can write content in it</li>
  <li>Once an editor has put content in a cell, <em>only him and document owners</em> should be able to edit it further</li>
  <li>If a cell is cleared by its author or one of the document's owners, the protection should automatically be removed as well so any editor can now edit it (back to step 1)</li>
  </ol>
  
  <p>I'm trying to use <a href="https://developers.google.com/apps-script/" rel="nofollow noreferrer">Apps Script</a> to do this, but it looks like that you can't <em>remove</em> a <a href="https://developers.google.com/apps-script/reference/spreadsheet/protection" rel="nofollow noreferrer">Protection</a>, nor get the list of protections that apply to a specific cell.</p>
  
  <p>Is it even possible to do this?</p>