Those that suggested physical destruction have not answered the question.

DBAN, Data Removal: Darik's Boot and Nuke - DBAN, will wipe your drive very well for free.

Did you read what it says on the link?

"While DBAN is free to use, there’s no guarantee your data is completely sanitized across the entire drive."

Also, some people have computers where they don't even know the Windows password, or the operating system will not start. That is why physical destruction is the only sure way to render the hard drive unusable.

BBQ the Hard Drive case at 400 degrees for 4 minutes; that will melt and destroy the disk that holds the information inside the hard drive..
For those that are thinking of asking how it tastes, no need to, it's Wonderfull and very filling! :icon_wink:

Go on Google and search for "DoD wipe". Look for one with a seven wipe selection.

30+ year of experience IT guy here. Put it in the oven on a cookie sheet on top of foil or parchment paper for 15 minutes at 400F. Zero chance it will be readable after that.