How do I delete contact suggestions from Messages in OS X? In the "To:" box in the Messages app on OS X, when I start typing in a contact name, I get old "iMessage" contacts which I've long since deleted. They certainly don't exist in my contacts; the only place I think they could exist is in my iMessage History somewhere on the iCloud servers. In any case, how can I delete them? Thanks.
The answer provided by @Noldorin works for me: 


  Messages on OS X doesn't allow "Recent" contacts to be deleted, but
  Messages on iOS does allow this. An oversight by Apple, but this is a
  fix nonetheless.


To clarify, I looked at recent addresses on my iPhone/iMessage when starting a new conversation. There's an "i" symbol which allows your to see recent group conversations and addresses, and also a remove button.

Once removed the erroneous address is no longer visible in OS X iMessage.