Although no longer recognised as a popular operating system, Microsoft DOS is widely used for troubleshooting and diagnostic purposes. MS-DOS is composed of hundreds of commands to help you execute, copy, modify and erase files. A typical way to permanently remove files from an SD card or other storage unit is by formatting it. Such command may be efficiently executed through various steps within DOS mode.
Insert your SD card into your memory card reader. Connect the memory card reader into any available USB port on your computer. Allow your system to recognise the device.
Click "My Computer" and take note of your SD card drive letter. Such letter is assigned next to the volume label. For example, it typically states "Removable Storage (drive letter)."
Click the Start menu and type "CMD" from the Run command. Press "OK" to launch the DOS Command Prompt. Another way to access DOS is by turning on your computer and pressing "F8" during computer start-up (prior to seeing the main Windows logo.) Select "Safe Mode with Command Prompt" from the list of options shown.
Access the SD card by typing its drive letter, followed by a colon, and press "Enter." An example of this would be "L:" without the quotes. Type "Format L:" and press "Enter" to permanently delete your SD card's contents. Note that "L" merely represents your own drive letter assigned by your system. Once finished, type "Exit" to shut the DOS Command Prompt.