When you are erasing data or deleting a partition on a hard drive, only the file system's record of that data is erased, and the actual data remains until it is overwritten. To remove the data with no chance of recovery, you need a special program that writes over the old data with junk data at least once, though several times is optimal. For partitions on an external drive or an internal drive, except for the main Windows partition, you can use Aoemi Partition Assistant Standard Edition to securely wipe the partition. To wipe the main Windows partition, you will need a self-booting tool, such as Darik's Boot and Nuke.

Wiping With AOEMI Partition Assistant

Step 1

Install AOEMI Partition Assistant (link in Resources), which is a freeware partition manager for Windows. Start the program once the installation is complete.

Step 2

Right-click on the partition you would like to wipe and select “Wipe.” Choose the number of times you would like to wipe and fill the partition with junk data, then click “OK.” The more times the data is overwritten, the harder it will be to recover, though each wipe takes a significant amount of time.

Step 3

Click the “Apply” button in the program's toolbar, then click the “Proceed” and “Yes” buttons to start the process. Afterwards, the partition will be deleted, leaving only unallocated space. If you would like to create a new partition in the space so that the partition is recognized by Windows and immediately usable, right-click the partition and select “Create Partition.” Choose the size of the partition and the file system, usually NTFS, then click “OK.” Click the “Apply” icon to create the partition. Reboot afterwards to complete the changes.

Wiping With Darik's Boot and Nuke

Step 1

Download the newest version of Darik's Boot and Nuke(link in Resources) which is a free secure-erase program in an ISO disc image format.

Step 2

Insert a blank disc into your CD or DVD burner and browse to your “Downloads” directory using File Explorer. Right-click on the ISO file beginning with “DBAN” and select “Burn Disc Image.” Once complete, reboot the computer with the disc in the drive.

Step 3

Press the “F12” key, or the required key to access your machine's boot menu or boot order settings. Refer to your computer's documentation, if necessary. Choose the option to boot from the CD or DVD drive.

Step 4

Press the “Enter” key to select “Interactive” mode. Using the “J” key to move up and the “K” key to move down, select the partition or drive you would like to wipe and press the “Space” or “Enter” key. Change the number of wipes by pressing the “R” key, typing a new value and pressing “Enter.” Select the write method, if desired, by pressing the “M” key. Press “F10” to wipe the drive.

Step 5

Remove the CD or DVD and shut down the computer when finished. If all partitions have been wiped, the drive is now empty and will require an operating system to be installed before it can start a computer properly.