I was long aware that all the big social networks had stolen your contacts when you installed their apps on your phone. What I didn't know, is how to delete them, but for my surprise, there seem to be easy ways to do this. I'm not fooled: they are most probably just archived, but this is better, than nothing.
- Manage Invites and Imported Contacts1
- Imported contacts2
- Manage your contacts3
This really, really should only be allowed as opt-in, not as default.