Managing iLife Asset Management I log into my Mum's computer with my iCloud account, and I've found that it has copied over 70Gb of my photos to the iLifeAssetManagement folder in user account on her computer.

Her MacBook Air is now complaining about lack of storage space. I scratched my head rooted around and found it was down to this "feature".

Deleting will only mean it will return; however can I turn this off?

Perhaps I should just decouple my iCloud account from being on her computer, but it is handy for Facetime, etc.
You can disable Photostream by going to System Preferences -> iCloud and deselecting Photostream (and any other iCloud synchronisation you don't need).