Flattening and disabling the submit button after sending

Flattening fields and comments can be achieved using this code:

this.flattenPages();

Note that this doesn't mean the user can't edit it. If they have Acrobat they could still do that. In order to prevent editing you should digitally sign and lock the document.

To hide a field using this code (replace the name in quotes with the actual field name):

this.getField("Submit Button").display = display.hidden;