If you want to quickly disable chat with with particular contact on Facebook:
Open a chat window with your contact.
Click the gear located at the top right of the window and select "Turn off Chat for ..."
To revert the changes, follow the below procedure:
Click on the gear icon at the bottom of the chat window > Advanced settings
In the window that opens, select "Turn on chat for all friends except" and clear the names for the contacts you want to restore the chat feature:
Click on Save.
CCM is a leading international tech website. Our content is written in collaboration with IT experts, under the direction of Jeff Pillou, founder of CCM.net. CCM reaches more than 50 million unique visitors per month and is available in 11 languages.