How can you stop a message from being sent on Facebook?

I'm not sure that you can turn off the chat feature on Facebook. But you can prevent people from chatting with you by going offline. You do this by clicking the chat button on the bottom right. Then next to the titles of different groups of friends there is a green circle in a slider click to the right of it in the slider. It will then minimize the group and it will say offline. You can do this for each group. And voila you don't have to talk to anyone via Facebook anymore.