Seriously, all that is required is removal of the hard drive and a hammer. Pound the HD to dust and no-one is ever retrieving that. Nice new clean HD and fresh OS install and it's all over but the crying. If I had the slightest inkling that "The Boys" were coming to seize my PC and there was even the slightest notion that there might even be something there...that's precisely what I would do.
AL, the CT school shooter deleted his hd then smashed the crap out of it with a hammer and screwdriver. LE computer forensics were still able to retrieve loads of data from his HD