I updated the accordian to the latest version (2.1.0) in DMX extension manager. Opened DW2017, opened a page using the accordian (from earlier accordian 2 version) and it updated it, synced some files, etc.

If I open Scriptfiles/dmxAccordion.js it says at the top:

/*
DMXzone Accordion
Version: 1.1.2
(c) 2013 DMXzone.com
@build 12-08-2013 10:49:07
*/

How do I make sure all files are updated? This would appear that it did not update everything....?

Hi David,
Accordion 2 js file must show version 2.0.
As any other upgrade procedure, please remove the js file locally and reapply the extension so it can create the new js file.. then upload to your server.

Are there any other files that need to be manually removed? And what is the best way to "reapply" the extension? Does that mean uninstall it, and reinstall it?

To reapply it, means to open the extensions settings and click ok ...