I Order Terms

1. You can download and install “I Order Terms” plugin by using the built-in WordPress plugin installer. Or you can upload plugin folder “i-order-terms” manually to your “/wp-content/plugins/” directory.
2. Activate the plugin through the “Plugins” menu in WordPress.
3. You will need to enable plugin for taxonomy that you wish to sort.

Enabling plugin for taxonomy

You can use the settings page or add code in your function file. There are two options you can use to make taxonomy sortable:

1) You can enable sorting when registering taxonomy:

register_taxonomy( 'your-taxonomy-name', 'your-post-type', array(
    'label' => __('Category'),

    // this parameter is used to enable
    // sorting for taxonomy 'your-taxonomy-name'
    'i_order_terms' => true,
));

2) Other option is to pass an array of taxonomies (or tags/categories) via filter “i_order_terms_taxonomies” in your functions file like this:

function custom_i_order_terms_taxonomies($taxonomies) {
    $taxonomies = array_merge($taxonomies, array('taxonomy', 'category'));
    return $taxonomies;
}
add_filter('i_order_terms_taxonomies', 'custom_i_order_terms_taxonomies');

This will enable taxonomy sorting for ‘taxonomy’ and ‘category’ taxonomies.
Naturally, you will have to provide your taxonomy names.