I don't recommend to do that because you can't run OS X on a virtual machine created on Windows. However, you can install OS X on a virtual machine if you create it on OS X.
You shouldn't delete OS X. Instead, use Boot Camp to install Windows (now, install Windows 7 because Windows 8 isn't supported) and your Mac will start onto Windows by default. When you need to start into OS X, press X key while your Mac is starting.
If you need help to install Windows, see > http://manuals.info.apple.com/en_US/boot_camp_install-setup_10.7.pdf