add to functions.php
in your theme:
function dougbeal_unregister_categories() { register_taxonomy( 'category', array() ); } add_action( 'init', 'dougbeal_unregister_categories' ); unregister_widget( 'WP_Widget_Categories' );
https://wordpress.stackexchange.com/questions/120418/completely-disable-categories
http://stackoverflow.com/questions/4249694/how-do-i-remove-a-taxonomy-from-wordpress