I am doing this in Magento 1.9 CE, and my objective is to log out the user as soon as the password is changed.

1. I registered my extension.

app/etc/modules/Bmg_Golo.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <config>
        <modules>
            <Bmg_Golo>local</Bmg_Golo>
            <active>true</active>
        </modules>
    </config>

2. My config.xml

app/code/local/Bmg/Golo/etc/config.xml

    <?xml version="1.0" encoding="UTF-8"?>

    <config>
        <modules>
            <Bmg_Golo>
                <version>0.0.1</version>
            </Bmg_Golo>
        </modules>
        <global>
            <models>
                <bmg_golo>
                    <class>Bmg_Golo_Model</class>
                </bmg_golo>
            </models>
        </global>
        <frontend>
            <events>
                <controller_action_postdispatch_customer_account_resetpasswordpost> 
                    <observers>
                        <bmg_golo>
                            <type>singleton</type>
                            <class>Bmg_Golo_Model_Observer</class>
                            <method>logout</method>
                        </bmg_golo>
                    </observers>
                </controller_action_postdispatch_customer_account_resetpasswordpost>
            </events>
        </frontend>
    </config>

3. I created an observer.

app/code/local/Bmg/Golo/module/Observer.php

    <?php
    /**
    * 
    */
    class Bmg_Golo_Model_Observer
    {
        public function logout($observer) {
            $session = Mage::getSingleton('customer/session');
                if ($session->isLoggedIn()) {
                    Mage::getSingleton('customer/session')->logout();
                }
        }
    
    }
    ?>

My customer logged out after changing the password. I doubt the event/observer in config is wrong and my method in the observer is not getting called. Please help me as I am new to Magento.