How remove theme default image sizes. WordPress example

function somarket_remove_default_image_sizes( $sizes ) {
	return array_diff( $sizes, array(
		'boxstyle-small',
		'boxstyle-medium',
		'boxstyle-large',
		'boxstyle-list',
	) );
}

add_filter( 'intermediate_image_sizes', 'somarket_remove_default_image_sizes' );