Remove timthumb? How to?

I am currently using a plugin to generate ‘popular posts’ for a site I am maintaining. I want to set up Photon CDN (…well, activate it), but when I do the plugin no longer generates thumbnails for the popular posts.

The plugin generates the thumbnails using tim thumb, whereas Photon generates thumbnails in it’s own way, so they are conflicting and throwing errors.

How can I disable tim thumb, or at least generate all thumbnails only through Photon?