You probably already know that hiding hard drive partitions on Windows involves the old school trick, where you edit a couple of registry keys, and the partition becomes invisible instantly. To get it back simply revert the changes in the registry.
But why mess with registry when you can do the same thing with this handy utility, NoDrives Manager.
NoDrives manager is a small and lightweight utility that doesn’t even require installation. Just download it from this link, unzip it and double click on the executable file to launch it.

To hide a drive/partition select it and then click on Hide All Drives button. To unhide them again, simply do the reverse. Isn’t this easy :)
Enjoy!

Wow, wonderful tool, why you use it is a matter of choice ;-)
I know what you will use it for ;)