wp_delete_attachment_files()
Function: Deletes all files that belong to the given attachment.
Source: wp-includes/post.php:6118
wp_delete_file_from_directory()
Function: Deletes a file if its path is within the given directory.
Source: wp-includes/functions.php:7500
wp_normalize_path()
Function: Normalizes a filesystem path.
Source: wp-includes/functions.php:2155