How to Securely Erase Flash Drives

By Marshal M. Rosenthal

A flash drive, like any data storage device, does not guarantee that a file deleted from it cannot be restored. A user who wants to securely erase a flash drive, totally wiping clean any data, must have a format utility that works with the computer's operating system. Mac computers include such a utility, and for Windows computers there are a number of free format utilities.

Things You'll Need

  • Format utility applicable to operating system

Securely Erasing with Windows

Step 1

Plug the flash drive into a USB port on the computer. Download and install a format utility (see links for examples in Resources). Restart the computer after the installation is completed.

Step 2

Launch the format utility; click "Start," then click "All Applications" and choose the flash drive from the "Devices" or "Drive" drop-down menu, depending on the particular format utility’s main screen.

Step 3

Click the "Options" button at the top of the screen. Select the "Erase" tab at the top of the window that appears.

Step 4

Check the "Block erase" or "Secure erase" box in the window. Click the "Apply" button. Click the "OK" button to close the window.

Step 5

Click the "Format" or "Start" button at the bottom of the format utility’s main screen. Click "Yes" or "OK" in the confirmation pop-up window.

Step 6

Wait as a series of lines scroll down the center of the program’s screen. Click on the "Done" or "OK" button in the "Format confirmation" window when it appears; this could take up to four hours or more, depending upon the size of the flash drive.

Step 7

Quit the program. Right-click on the icon of the flash drive on the desktop. Select "Eject" from the pop-up menu. Remove the flash drive from the USB port.

Securely Erasing with Mac

Step 1

Plug the flash drive into a USB port on the Mac. Launch the "Disk Utility" program in the Mac’s operating system by double-clicking on it. The program can be found by clicking on the "Applications," folder, then clicking the "Utilities" folder.

Step 2

Click once on the icon of the flash drive in the left column of the Disk Utility program’s main screen. Click the "Erase" tab at the top of the screen.

Step 3

Select a format from the "Format" drop-down menu; for example, "MS-DOS (Fat)" or "Mac OS Extended (Journaled)."

Step 4

Click the "Security Options" button on the window to open a new window.

Step 5

Check the "35-Pass Erase" box near the bottom of the window. Click the "OK" button to return to the previous window.

Step 6

Click the "Erase" button at the bottom right of the window. Click "Erase" in the confirmation pop-up window.

Step 7

Wait as lines scroll up the center of the window as the flash drive is securely erased; this procedure can take up to four hours or more, depending on the size of the flash drive.

Step 8

Click the "Eject" button at the top of the window to eject the flash drive from the Mac once the scrolling lines stop. Quit the Disk Utility program. Remove the flash drive from the USB port.

Tips & Warnings

  • Make sure there is no data you need on the flash drive before you securely erase it.
  • Stopping a format in progress will cause disk errors on the flash drive.
  • Do not use a USB hub to connect the flash drive, as they are less reliable than a built-in USB port.