After years of relying on the same old PCs, you’ve decided to finally upgrade your hardware and exchange it for top-of-the-line equipment. You anticipate the boost in productivity, and you envision how the sleek new towers and monitors will look in your office.

But to help cover the costs of replacing your computers, you want to sell the old ones. You know the old ones have terabytes of personal information stored on their drives, and you don’t want the files falling into the wrong hands.

Before you simply hit the “Delete” button and ship your machine to its new owner, be aware that others can still recover your data.

How Do Others Recover Your Data?

When you delete a file from a typical desktop, the file moves to the “recycle bin” or “trash.” If you happened to delete those files on accident, this feature enables you to recover your old files quickly. Essentially, you’ve placed the intact data in a new location without erasing the file.

To erase the file, you have to empty the recycle bin—and even then, the information remains on your hard disk. How much of that information remains depends on your computer’s operating system and model.

Mechanical Hard Drives

Older computers often rely on mechanical hard drives with a spinning magnetic platter. Whenever you save a file, the drive magnetizes the disk. It later reads the changes in magnetization and interprets that information.

Since deleting a file would require the computer to change the magnetization on the drive, removing that information completely would take the same amount of time as initially saving the file. To save time, the computer marks the file as deleted, rather than truly erasing the contents. When you later save a new file, the computer overwrites the old files with the new information.

However, this process also enables others to recover your data. With the right software, individuals can scan your drive for marked-as-deleted data and restore them to the desktop.

Solid State Drives (SSD)

Unlike traditional hard drives, SSDs rely on flash cells rather than magnetization to store and retrieve data. Before it can write new data, the drive must erase any previous contents stored in the flash cells.

When you delete a file, the drive immediately removes all the data from the flash cells. When you delete information from this system, you cannot recover the data.

What Can You Do to Prevent Identity Theft?

If you have a PC with a solid-state drive, you only need to reinstall your current operating system to remove any personal information and data.

However, if your older computer has a traditional drive, you’ll need to use the following techniques to ensure your files stay deleted.

Wipe Your Drive

You can download several disk-wiping tools like CCleaner or Eraser to wipe your drive and free space. These programs write other data over your hard drive to erase sensitive information. And they work well for deleting a few specific files from your computer.

However, if you worry that your entire hard drive may put your employees or clients at risk for identity theft, you may want to opt for more powerful applications, such as Darik’s Boot and Nuke (DBAN). This program completely erases everything from your hard drive, including your operating system. Then it overwrites these files with useless data.

Reinstall Windows

Does your computer run Windows 8? This operating system includes an extra feature that allows you to wipe your deleted files before you restore the operating system.

To reset your computer to its original factory settings, tap “Settings” and then “Change PC settings.” Next, tap “Update and Recovery”, and then “Recovery.” Under this tab, you can tap “Remove everything and reinstall Windows.”

From there you can follow the instructions on the screen. The program will ask you whether you want to erase the data quickly or thoroughly. If you erase the data thoroughly, your computer’s new owners will have a harder time recovering the data.

Destroy the Drive

Although the above steps should prevent data recovery, you can never be too careful with your customers’ financial information. If you feel deeply concerned about data recovery, you can hire a computer expert to degauss the drive. This process includes running a powerful magnet over the hard drive to wipe it completely clean.

Keep in mind that the degaussing process can cost a great deal. Most of the time, you won’t need to degauss your drive unless you store private health records, mission critical data, or personal identifying information.

Don’t Forget to Talk with Your IT Department

If you need help deleting old drives or preventing data recovery, talk with a computer technician for advice. He or she can determine which tools will work best for your business as well as guide you through the removal and restoration process.