That's virtual memory (the "page file"). I'm not sure if you can delete it, but I don't think you could do it while the OS is running (maybe from a Linux partition or something) without causing problems, and it will probably just pop right back up unless you disable the use of virtual memory. I don't know why you would want to do that, though. It allows you to use more memory than you have as RAM by swapping unused stuff out of memory into it and then back when it's needed. It's basically the same as a swap partition under Linux.