Two ways to delete WP taxonomies and their terms

gistfile1.txt

<?php

register_uninstall_hook( __FILE__, 'do_delete_terms_wpdb' );
/**
 * Delete database entries of terms and taxonomies using wordpress SQL api $wpdb 
 *
 * @global  $wpdb
 * @wp-hook register_uninstall_hook
 * @author  Travis Smith
 * http://wpsmith.net/2014/wp/plugin-uninstall-delete-terms-taxonomies-wordpress-database/
 */
function do_delete_terms_wpdb()
{
    global $wpdb;
    $taxonomies = array('term_1', 'term_2');

    foreach ($taxonomies as $taxonomy) {
        if (taxonomy_exists($taxonomy)) {
            // Prepare & execute SQL
            $terms = $wpdb->get_results($wpdb->prepare("SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy IN ('%s') ORDER BY t.name ASC", $taxonomy));

            // Delete Terms
            if ($terms) {
                foreach ($terms as $term) {
                    $wpdb->delete($wpdb->term_taxonomy, array('term_taxonomy_id' => $term->term_taxonomy_id));
                    $wpdb->delete($wpdb->terms, array('term_id' => $term->term_id));
                    delete_option('prefix_' . $taxonomy->slug . '_option_name');
                }
            }
            // Delete Taxonomy
            $wpdb->delete($wpdb->term_taxonomy, array('taxonomy' => $taxonomy), array('%s'));
        }
    }
}


register_uninstall_hook(__FILE__, 'do_delete_terms');
/**
 * Delete taxonomies and their terms using
 *
 * @uses    get_terms
 * @uses    wp_delete_term
 * @wp-hook register_uninstall_hook
 * @author  orionrush
 */
function do_delete_terms()
{
    $taxonomies = array('term_1', 'term_2');
    foreach ($taxonomies as $taxonomy) {
        if (taxonomy_exists($taxonomy)) {
            $terms = get_terms($taxonomy, array('fields' => 'ids', 'hide_empty' => false));
            foreach ($terms as $term) {
                wp_delete_term($term, $taxonomy); // delete each term
            }
            register_taxonomy($taxonomy, array()); // delete the taxonomy?
            //  unset( $wp_taxonomies[$taxonomy]);  // will this delete the taxonomy?
        }
    }
}