There are several ways to secure-erase your hard drive (e.g. SATA or SSD) before selling, gifting or otherwise disposing of it. Here are a few methods:

• Using the DISKPART command from a Windows command prompt that was opened with “Run as Administrator” option (this method of erasing is not as secure as the next methods),
• Purchase PARTED MAGIC (about $15), download and burn it to a USB drive or CD, and perform a “secure erase” or “enhanced” secure erase, or
• Download and use DBAN, which is Darik's Boot and Nuke, a free utility that you can download as an ISO file, then write/burn the ISO to CD, DVD or USB drive to make a bootable medium, and boot to and use DBAN to wipe single drives or multiple drives simultaneously using either Department of Defense 3-pass method (totally adequate) or the DOD 7-pass method. The easiest way is to boot to DBAN and then run it in interactive mode.

Writing/burning an ISO file to create a bootable USB drive could be done using RUFUS, a free utility. You can find your particular version of RUFUS here https://rufus.ie/en/ (the easiest way to select and download your appropriate version of Rufus, and some instructions for its use) and here http://rufus.ie/downloads/ (the more complex page to select your appropriate download, and without any instructions).

Writing/burning an ISO file to a CD or DVD could be done using various applications and utilities, such as BURN AWARE FREE found at https://www.burnaware.com/ and the download page https://www.burnaware.com/download.html. Please understand the difference between downloading the FREE VERSION of BurnAware versus the Free Trial of the paid version of BurnAware.

You can download DBAN Here: https://sourceforge.net/projects/dban/

If you buy Parted Magic, this describes how Parted Magic performs secure erase: https://partedmagic.com/secure-erase/