[Wiping clean external HD]

Thank you, it worked!

[Wiping clean external HD]

I am trying to wipe clean an external hard disk, but even selecting the "Entire Drive" option ends up with CCleaner permorming only a "Free Space Only" cleaning.

 

I suspect this might be because the external HD I am trying to clean was the HD of my previous laptop, and retains old system files on it (which is actually the reason I would like to wipe it clean).

 

What can I do to actually clean the entire drive?