How can I permanently remove a file from my computer?

Updated:July 2016

Sometimes the most secure way to keep something confidential is to get rid of it as soon as you don't need it. Learn how to erase files from your computer and wipe records of having sent something electronically.

First, the bad news: There’s really no such thing as permanently deleting information. Dragging files into your trash may appear to get rid of data, but in reality all it's doing is telling your computer to not show that information anymore, and that the space can now be used for something else. The file you thought was gone could be extracted if the person attempting to find it knows the right methods (chances are, they do). To make a file more unrecoverable, you need to over-write the data, or find ways to keep it off your device in the first place. That's what this page is about.

  1. How to wipe files on your computer
  2. How to keep your web browser from storing your activity
  3. How to wipe your computer when you're not going to use it anymore

Remove files more permanently

How can I permanently remove a file from my computer?
Removing data should be thought of as 'overwriting' data. Securely wiping content from your device means overwriting it several times.
Now for the slightly better news: All is not lost when trying to lose a digital file. What you want to do is to actually 'erase' data, not just delete it. It may sound like an issue of semantics, but when you erase a file, you're telling your computer to do something a little more than simply remove it from view.

Erasing (some systems call it "wipe" or "secure delete") overwrites the data several times, thus making more difficult to retrieve. Mac, Windows and Linux all include more secure methods of deleting files. You should find out the method that applies to your specific computer. Software such as Eraser or CCleaner offer useful shortcuts to over-write a file several times, rendering it, essentially, gone for good. 

For more information:

Keep your browser from storing your activity

You don't want the file on your computer after you've sent it, and you don't want to keep evidence that it was there, or that you've shared it with someone. You can limit the amount of information your browser keeps. Change your browser options to not save information locally.

Use ‘private browsing’ options to limit the ability of cookies to access information on your computer. Even with this, continue to regularly clear your browser history, and clear ‘recently opened files’ menus, and check for anything you may have left behind. You may also want to use Proxy services such as Tor to send files, keeping the destination from being traceable.

A number of plugins for browsers such as Firefox can provide further privacy options. For this, see our resource about online privacy.

Further information:

Wipe your whole hard drive

You may be in the market for a new computer, or it may be that you've done enough work on your existing one that it wold be easier to simply get rid of everything at once instead of looking around for each file you don't want to end up in the wrong hands. 

The best software for wiping your machine is DBAN. You'll need to install this on a CD or DVD and use that to boot your computer. Once in, you'll see several options. As you might guess: The more securely you want to wipe something, the longer it will take. Choosing "Zero Out Data," for example, will simply rewrite all the data on the computer one time. It's the fastest, but also the least secure of the options. The 7-pass option does the same thing, but seven times, and for possibly more security than many people require, set DBan to run the 35-pass option and go do something else for a long while.

Another method is to find and use a degausser - a machine that removes the magnetic field from your device, and thus all the data. 

After doing either of these two methods, if you're still worried about things, the only task that's left involves grabbing the screwdriver and a hammer. Physically take apart the the hard drive, find the disk and damage it. On the one hand, this may or may not be more than what's required, however, you might just find it a personally satisfying experience.

Further information:
Image credit: Screen grab by Kerry J.
Created: August 2013

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