Security by obscurity is not security.
If you are trying to protect information from the eyes of others, then encrypt it.
PGP, TrueCrypt are just two of many names ..... Google is your friend, take your pick.
On the other hand, if you just want to hide it because you can't stand the sight of it, I suggest you Google "remove my documents from start menu" .... there are various pages there professing to tell you how to do it. I have not tried any of the techniques, nor do I intend to, so do so at your own risk.