Prohibit user to create webform File field

I want to disallow users with webform creation permission to create webform "File" field.

The reason I want to do this is because I found that some of my users created web forms to collect information from visitors, and they include file uploading fields. However these files uploaded are placed inside the Drupal Public directory, which can be downloaded by the public if they discover their paths. Unlike other fields type, which are only accessible by certain roles with permission. This may causes information leakage.