Question

Is it possible to completely hide the department field called Choose a department on the pre-chat form?

Answer

There is no native setting that will remove the department field entirely. In your pre-chat form settings, unchecking Require Department doesn't remove the field from the pre-chat form but it will make it optional. 

However, you can hide the department field from visitors by using the Departments API end-point with an empty array.

<script type="text/javascript">
  window.zESettings = {
    webWidget: {
      chat: {
        departments: {
          enabled: []
        }
      }
    }
  };
</script>

Simply add the above code after your widget script on your website. It will look something like this: 

<script id="ze-snippet" src=[your widget key here]> </script>
<script type="text/javascript">
  window.zESettings = {
    webWidget: {
      chat: {
        departments: {
          enabled: []
        }
      }
    }
  };
</script>

This code prevents any visitors from seeing the department dropdown and therefore from selecting a department. It does not remove the department functionality from the chat entirely. You can still assign a department to a chat request on the back end using a trigger or the departments.select function.

For more information, see this article: Automatically route chats to departments.