From what you've described, the disk is not cleared of personal data. Formatting using the Apple disk utility does not remove personal data. However, the disk utility does give you the option to erase the disk and provides several security levels of erase to choose from.
You can also physically remove the hard disk from the laptop and erase the personal data using a SATA-USB interface (e.g., external hard disk enclosure) and a PC using PC disk utility software.