When you want to erase all data from your hard disk and make it as clean as possible, low-level formatting (or zero-filling) is the way to go. Low-level formatting is the process of completely erasing all the data on the hard disk, including the partitions and the operating system. Zero-filling is similar but omits options like disk geometry settings.

Before proceeding with low-level formatting, all the data on the hard disk should be backed up on another storage device since low-level formatting results in complete data loss.

Follow these steps to low-level format your hard disk:

1. Shut down your computer and disconnect all the external devices attached to it.

2. Turn on the computer and enter the BIOS setup by pressing the key on your keyboard (normally F2 or Delete).

3. Navigate through the BIOS to identify the hard disk you want to low-level format. Note down the model number of the hard disk.

4. Create a bootable USB drive or CD/DVD that has a low-level formatting tool on it. You can download and use the low-level formatting tool provided by the manufacturer of the hard disk or you can use third-party tools that are widely available.

5. Restart your computer and boot from the bootable USB drive or CD/DVD you created.

6. Execute the low-level formatting tool on your computer. Select the hard disk you want to low-level format from the list of available drives. Double-check the drive letter and model number to make sure you are formatting the correct hard disk.

7. Choose to conduct a low-level format or zero-fill based on your requirement. Both options erase all the data on the hard disk but do so differently. Follow the on-screen instructions to finish the low-level format process.

8. Once the formatting process is complete, remove the bootable USB drive or CD/DVD and restart your computer.

9. Reinstall the operating system on the hard disk after low-level formatting. The hard disk will be completely clean with no traces of the previous operating system or data.

In conclusion, low-level formatting is a powerful method to erase all the data on a hard disk and make it as clean as new. It is important to take all the necessary precautions before starting the low-level formatting process and to reinstall the operating system after completing the process.