On the plus page, on the chat section, click the down arrow next to your name, select "privacy settings" in the dropdown and uncheck everything. Voila, no more people.
Thanks. After selecting "Privacy Settings", you need to select "Custom" if "Circles" is currently showing for "Choose who can chat with you". Then it will show all the checkboxes. Mine showed up unchecked at this point, and a "Save" of this dialog removed everyone from my chat list (and I use psi on the desktop).
