Save space by removing Photo Stream photos from your Mac

2016 Update: If you use iCloud Photo Library, there's really no need for Photo Stream anymore except for niche use cases. I'd recommend disabling Photo Stream entirely if you use iCloud Photo Library.

iCloud's handy Photo Stream feature is very convenient for getting the photos you've taken to and from all your devices—Mac, iPad, and iPhone. However, if you use an app like DaisyDisk to find large directories on your Mac, you may notice a very large folder inside iLifeAssetManagement (specifically, in Users/[yourname]/Library/Application Support/iLifeAssetManagement/assets/sub).

You can safely remove this folder by doing the following:

1. Open System Preferences and go to the iCloud settings.
2. Uncheck 'Photo Stream' (this will turn off automatic syncing back to your Mac.

Now, you should get (in most cases) a few GB of space back on your computer. Note that you can still access all the Photo Stream photos you've previously imported into Aperture and iPhoto libraries.

If you want to enable Photo Stream again, you can. You might want to delete some files out of your photo stream (do this directly in Aperture or iPhoto), just to save space. You should only really keep files you'd like shared on all your devices in there.