When an image is auto-uploaded (i.e., using an upload mapping) it is an actual image on your Cloudinary account, detached from its origin. Therefore, in order to update it, as for any other "regularly" uploaded image, you should explicitly re-upload the image, overwriting the current one, while refreshing the CDN's cache as described here.
Alternatively, you can send a
destroy request. In both cases, you should either include the version or set
true. For example (in Rails):
Cloudinary::Uploader.destroy('sample', invalidate: true)
Note that it may take up to an hour (usually up to a few minutes) for the invalidation to fully propagate through the CDN while the 'version' component affects immediately.