Evacuation of a city?

[Ravenloff]

I have read through the manual (lightly) and played since release on Wednesday (heavily). I haven't been able to find a way to evacuate a city.

There are a number of uses for this, but the most significant one is destroying a city you know you're going to lose to avoid it falling into enemy hands, loosing treasury for its lose, and possibly giving them a tech in the process.

Am I just not seeing the button?