If you’re planning to dispose of a PC by giving it away, selling it, or discarding it, your top priority should be making sure that no personal information is left on the device. The same is true if you’re recycling a hard disk drive or USB flash drive.
The first step with a PC is to reinstall Windows, using the option to delete the existing partitions on the device and then do a clean install. For a secondary disk, you can use the Format command to erase any existing content. But that still leaves the possibility that some data will still be available in the erased space, where a determined spy could recover it using a disk utility.
The solution? Encrypt the disk before formatting it. Without a recovery key, any recovered data will be unreadable. The easiest way to accomplish this on the system drive is to open an elevated command prompt and run the following command:
If you’re working with a secondary disk, substitute the drive letter for that drive.
The /w switch stands for wipe, and the result is the effective obliteration of every bit of data in unused disk space, leaving existing files untouched.