gg,
Errrr there's an option to allow you to clean free space, it's the first option.
Do I have to spell it out ?
Cleaning "free space" is about as much use as waving a dead chicken over your computer.
Cleaning "free space" assumes you have correctly identified
ALL personal files on your computer and securely deleted them. Something which, let's face it, your average home user won't be able to do because they'll have files in numerous different formats scattered all over their PC.
The only safe options are :
(1) A complete wipe using an appropriate tool such as DBAN
(2) Removing the drive