Answered How to remove plugin after updating an extra?

if ($object->xpdo) {
    $modx =& $object->xpdo;
    switch ($options[xPDOTransport::PACKAGE_ACTION]) {
        case xPDOTransport::ACTION_INSTALL:
        case xPDOTransport::ACTION_UPGRADE:

        $obj = $modx->getObject('modPlugin', array('name' => 'MyPlugin'));
        if ($obj) {
            $obj->remove();
        }

    }
}

return true;