Thank you for your reply.
I just tested it again after clearing the cookies, but still didn't log out the user.
Could this be because I have the option "Remember me" enabled on log-in?
I did var_dump($logoutInfo); and this is what I got:
Code:
array(2) { ["sessionhash"]=> string(32) "78370741ecec09885430016ec4c991fa" ["apiaccesstoken"]=> NULL }
I'm not sure if this would help.