If you want to prevent a friend or group of friends from calling or chatting with you: Create a friend list that includes the people you`d like to prevent from chatting with you. You can also use any existing friend list you`ve created. Click the actions menu in the bottom right corner of the messaging sidebar. Select Limit Availability... Check the box next to the friend list you don`t want to be available to chat with and click Close. You can also select Only make me available to: from the menu and check off the friend lists you want to be able to chat with. Note: To stop someone from contacting you, you can also unfriend the person or block the person from interacting with you in any way on Facebook.Someone said: When I click on Limit Availability there is no box next to my friend list.