Format hard drives securely by using the windows command line utilities cipher and format, cipher can be used to wipe empty disk space, but if you perform a format of the drive, then the entire drive will have empty disk space allowing for a secure delete by overwriting with zeros then ones followed by random numbers.

Step 1: Format the Drive

Step 2: Open CMD

Press Windows+R to open “Run” box. 
Type "CMD"
Click OK

Step 3: Run Cipher

cipher /w:<driveletter>:\

Step 4: Run Format

format <driveletter>: /fs:NTFS /p:7