Remove sidebar, supporting snippet for body class

add_filter('body_class', 'remove_sidebar_class_for_month_view', 50);

/**
 * Remove the .sidebar body class from month view.
 */
function remove_sidebar_class_for_month_view(array $classes) {
    // Don't interfere if the request does not relate to month view
    if (false === (tribe_is_event_query() && tribe_is_month())) return $classes;
    $match = false;

    // Search for a match
    foreach ($classes as $index => $class)
        if ('sidebar' === $class) {
            $match = $index;
            break;
        }

    // If we found the .sidebar class then remove it
    if (false !== $match) unset($classes[$match]);
    return $classes;
}