Written by Greg Kjono
There are a couple of hidden files that typically use up a lot of disk space, especially in systems that have large amounts of RAM. These are the pagefile.sys and hiberfil.sys. Hiberfil.sys can be deleted if you don't use the hibernation feature. Instructions on how to do that are available at http://nerdsknowbest.blogspot.com/2013/01/how-to-delete-hiberfilsys-on-windows.html.
I don't recommend completely removing the pagefile, especially on desktops and laptops, however. You can configure them to not use so much disk space though. By default they are set to "system managed" and are probably close in size to the amount of memory you have in your PC. Chances are that you aren't actually using most of that space in the page file, and that your computer is just allocating that space in case it needs it in the future.