permanently delete files from laptop - how?

[kkkkkkate]

Hi, I found a good Mumsnet thread on this recommending 'Eraser 6', but each time I try to use it, it seems to chuck lots of adverts/rubbish onto my computer
Can anyone recommend a foolproof way of doing this?
MTIA

CCleaner will wipe an entire drive.

Some versions of McAfee AntiVirus have a Shredder to delete individual files.

Thanks nannynick!