When I signed into Google+ today, I saw a few people who I was not expecting in Chat. After trading a few cat pictures, I decided to set things back to the way they used to be. Here is a handy guide:

How to Change Your Google Chat Privacy Settings

* Look for the "Chat" title on the left of your stream.
* Click on the grey arrow to the right on that title.
* From the dropdown that pops up, choose "Privacy Settings."
* On the panel that pops up, click on the "Choose who can chat with you:" dropdown, and select the option "Custom."
* Go through the list of Circles, removing any you would not like to chat with you.
* Click "Save."