How do you turn chat off in stardoll?

You can't. Stardoll is basically a a Dictatorship and doesn't want users to turn chat off because that would give them some control over their experience of the game. Or, you could send your question to them, but good luck getting a real answer because their answer to everything is:

Thanks for your mail.

We are experiencing some difficulties with this item/function. We are aware of the problem and will fix it as soon as possible.

We are sorry for the inconvenience!

Kind regards,

The Stardoll Staff