What happens if you cancel the Drive Overrwriter from Ccleaner?

CCleaner for Windows
1

If you let Ccleaner use for instance Drive Wiping with three passes and you cancel it at 80%.

Does that mean that 80% are securely deleted and 20% not even if you canceled it?

2

Roughly speaking, yes.

3

Also you notice a lot of lost space on the disc taken up by wipe files