Unable to remove image sizes

I’m trying to remove 15 or so unnecessary thumbnail sizes and would like to regenerate and remove them from the server.

I started with a few sizes and tried this code in the functions.php file

function remove_default_image_sizes( $sizes) {
    unset( $sizes['portfolio-square']);
    unset( $sizes['portfolio-landscape']);
    unset( $sizes['portfolio-portrait']);
	unset( $sizes['portfolio-default']);
    unset( $sizes['portfolio_masonry_regular']);
    unset( $sizes['portfolio_masonry_wide']);
    return $sizes;
}

add_filter('intermediate_image_sizes', 'remove_default_image_sizes');

and those sizes are still showing in the Thumbnail Size list on the Regenerate Thumbnails page.

Any suggestions?

I’m not familiar with using the WP-CLI