i need some computer help/advice

i need to delete a few files/spreadsheets from my computer, and i want them permanently off of the computer so nobody would ever be able to get to them again.
how would i go about this? i know that just simply clicking delete does not do this, so any help is very helpful.
thanks.
 
if you hold down the SHIFT key when you hit the DELETE key, then it does not put the file(s) in the recycle bin; they are deleted permanently

you can also just empty the recycle bin after deleting them.
 
look for a file shredder program. I think spybot s&d has one built into it....It won't be gone completely, but you pretty much have to destroy the drive for that.