How to Completely Wipe a Hard Drive in Windows 10/8/7?

Method 1: Completely wipe computer by resetting your PC
This method wipes computer by using the reset feature in Windows 8.1 or 10 during reinstalling operating system, which has an option to remove everything on hard drive. This section takes Windows 10 as example to explain how to wipe computer completely. If your computer is running an older version of Windows, you can try steps in Method 2 to erase hard disk.

Step 1 Click "Start" menu and select "Settings" option. On Windows Settings pane click "Update & Security" option.

Step 2 Click "Recovery" option on the left navigation options and then click Get "Started" button under "Reset this PC" section.

Step 3 Select "Remove everything" option which removes all of your personal files, apps, and settings and start over.
Step 4 Select "Remove files and clean the drive" when you are asked to whether to clean the drives too. The cleaning process may take longer time but it makes sure no one can recover erased files.
Step 5 Click "Next" and "Reset" button on following steps to complete the task.

Method 2: Wipe hard drive using free hard drive eraser software
The secure way to erase data for good is overwriting data and refill hard disk using zeros or random data, so that nobody can recover wiped data with disk recovery software. Sounds complex? Actually, nowadays cleaning hard disk is not a complicated work, and you can easily and securely erase disk using disk wipe software.
Free hard drive wipe software - DiskGenius Free Edition
DiskGenius is free software for permanently data wiping. With this hard disk eraser, you can wipe all data on by filling disk sector by sector, making files unrecoverable. Besides, it is a free partition manager program which is able to resize, format, clone or backup partition, check &repair bad sectors, backup data, etc.

*Case 1: Safely erase secondary HDD / external hard drive / SD card / USB flash drive
Step 1 Connect the removable device to your computer and make sure it can be recognized by Windows.

Step 2 Install and run DiskGenius from your PC and you can see all local disks and portable devices on the main interface.

Step 3 Select the external hard drive or SD card you want to erase data, and select "Erase Sectors" option under Tools menu.
Step 4 Select items to fill disk sectors and click Erase button on the popped-up window.
There are four options to fill disk sectors in the drop-down list, i.e. Random Data, 00, FF and User Specify. You can either choose one from "00, FF and Random Data", or specify item to fill disk.
Step 5 DiskGenius asks confirmation for the action, click Erase button to continue.
Since the process wipes data permanently, you should make sure you are erasing correcting disk and important files have been backed up.

Step 6 The disk eraser starts wiping data on selected drive and the process may take long time if the disk has very large capacity.

Case 2: How to wipe computer system hard drive?

In this example, you can learn how to wipe a computer's main hard drive where Windows is installed. Operating system does not allow to erase system while it is running, and we can only wipe non-system partitions. In this situation, we can erase the hard disk in Pre-OS environment, for example Windows PE.
DiskGenius is able to reboot to its WinPE version directly from Windows as well as creating bootable USB disk with which you can boot computer and run the WinPE version. If you want to create a bootable WinPE USB stick, you can insert your USB flash drive and click Tools menu and select "Create WinPE bootable USB drive of DiskGenius". The following steps show how to reboot computer to WinPE version directly and then erase system disk.

Step 1 Launch the free disk wipe tool DiskGenius from your Windows computer.

Step 2 Click menu "File" and choose "Reboot to DiskGenius WinPE version" option.
Step 3 It takes about two minutes to create booting information for Windows PE, please wait it to complete with patience.
Step 4 Once the application is ready to reboot, it prompts to restart and backup data. Click "OK" button and computer reboots.
Then the DiskGenius WinPE version is launched, which contains same features with the Windows version.

Step 5 Select computer's system hard drive where Windows is installed and click "Erase Sectors" option which can be found under Tools menu.

Step 6 Click Erase button and the software starts wiping the disk.

Note: Once the process finishes, the computer cannot boot to system, as system partition have been erased. You need to make a clean system installation on the hard disk.

Case 3: Wipe a single file or folder on hard drive

Erasing an entire hard drive takes too much time, and you don't have to do that if you just want to erase certain existing files on the disk. On account that deleting files by emptying Recycle Bin does not wipe data complete, we should do extra operation to make files unrecoverable. Files deleted in this way cannot be recovered by any recovery software or professionals. Let's have a close look at how to wipe files and folders:

Step 1 Launch DiskGenius again, and locate files you want to permanently delete. Select those files and right-click them to choose "Delete Files Permanently".
Step 2 Click "Permanently Delete" button on the popped-up window.

In order to completely delete the file, the application will refill hard drive sectors taken by the file during deletion. By default, it overwrites data by filling zeros which can be modified to random data as well. Besides, you should select "Delete Directory Entry" option on FAT partition (and the option will be "Delete File Record in $MFT" on NTFS partition).
Step 3 Click "Delete" button to confirm the action to be done.
When selected files get deleted, you can continue to delete other data on your computer.

Case 4: Erase deleted files only without affecting existing data

Erasing free space on hard drive overwrites lost files, which does not disturb existing files on the disk. This solution applies to those who just want to overwrite lost files only in order to make lost data unrecoverable. For instance, you've formatted hard drive and reinstalled operating system, what you need to do is erasing all disk area except system; or you've deleted sensitive using Shift + Delete, and want to make sure they are no longer recoverable without affecting existing data.

Step 1 Start Eassos DiskGenius, click "Tools" menu and select "Erase Free Space" item.
This function permanently erases unused free disk space, preventing data from being recovered.
Step 2 Select partition / disk for which you want to erase free space and click "OK" button.
Step 3 Select characters to overwrite disk space and click "Erase" button.
Step 4 The application starts cleaning unused disk space, which takes long time if free space is very larger.

Method 3: Clean PC hard drive by physically destroying it
Physically destroying a hard drive is also a solution to ensure data is forever unrecoverable. If you are not going to reuse or recycle your hard drive, you can try this solution to clean data.

Step 1 Use a screwdriver to remove all screws on the hard drive case. Then you'll be able to remove enclosure and the main circuit board.

Step 2 Remove platters and heads out of hard drive enclosure, and use a hammer to hit platters. Then repeatedly strike other components.

Step 3 Box up all components and throw them to garbage can.