Custom image sizes and unregistering unused ones for WordPress

functions.php

<?php
// This removes the hard limit and oprhan originals
add_filter('big_image_size_threshold', '__return_false');
// This is pretty nice custom skipper
add_filter('intermediate_image_sizes_advanced', 'remove_default_images');
function remove_default_images($sizes)
{
    //unset($sizes['small']); // 150px
    //unset($sizes['medium']); // 300px
    unset($sizes['large']);
    //unset($sizes['medium_large']);
    unset($sizes['1536x1536']);
    unset($sizes['2048x2048']);
    return $sizes;
}
update_option('medium_large_crop', 0);
update_option('medium_large_size_w', 760);
update_option('medium_large_size_h', 0);