Facebook allows users to chat with their friends once they login to their account. The default Facebook Chat status is set to Online and you can go offline using the Chat Options link
Navigate to the Chat section displayed on the bottom right corner of Facebook portal. This would display the Friends list who are available for chat along with the Options link.
Clicking the Options link would launch the below displayed menu option. To turn off the Facebook Chat, select Go offline from the list of menus.
Your Status would now be displayed as Offline under the Facebook Chat section.