Is it safe to delete uploaded photos if Photon (Jetpack) is activated?

Even if the CDN images are cached “forever”, I would not recommend deleting them from your upload folder.

You might later decide to deactivate JetPack because:

  • you want to use another CDN and you only use JetPack for the Photon service.
  • it somehow becomes incompatible to your later setup
  • or because of possible temporary bugs in JetPack.

Not all of your images might be served by the CDN, e.g. attached ones but not used and also images that are not in posts or pages.

Reusing images in your posts or pages becomes harder, without the use of the Media library.

An edge case could be that if the site would somehow violate the terms of the service, then it could be suspended from it.