if you want things gone you need to get a shredder as long as it shreds best 1 i suggest is evidence elminator that has all these kinds of methods of shreading..
then to offically make it gone you format 10 times in a row.. just format as soon as that is done do it again.. and then do it again over and over 10 times things will be gone. or least make it like 2 years for them to recover it