Simple answer... Can't.
Complex answer... Depends on just exactly WHO is interested and just exactly HOW interested.

If... IF... If you have been 'up to something', shall we say mega-naughty, you are a fool to allow any physical remnants of any HDD to be anything other than dust. By 'dust' I mean incinerated and mechanically ground to fine dust.

Don't believe me ?
Check out a very well known specialist data recovery company in Germoney !

(No, I am NOT going to provide a link here.)

__________________
Fusion for REAL!--CDex 1.51--Wackyuses--Bitzi - Check Files Before Download !--.mp3 File Name Change Problems? Try Rename-It!--Alternate PORTS--Avast- Anti-Virus--WindowWasher--IrfanView--PC Pitstop - Test your PC !--Mac OSX Troubleshooting--GO .ape ! - For 'Lossless' Audio Compression--Port :6346 - Test If It Is 'Blocked'--Cole2k Codecs--OldVersion - Newer isn't always better !
Nod32 - Free Virus Scan: Use ESET's Online Antivirus Scanner

Tomorrow's forecast:
Sunni in places, Shi'ite in others...