a simple format of the drive is good enough depending what you are trying to do and/or what you are trying to hide, are u just trying to erase stuff off a harddrive so it is not accessible any more ever again?if so format the drive and then put files on it, and hten format and repeat 4-6 times, this will fragment the drive and overwrite the files making it difficult for the best of programs to pull data off of but like always it is never perfect and some of the best people can gather data off of them one way or another