There are a number of ways to get to it, but you're looking for a Control Panel function called "Create and format hard disk partitions". Easiest way is to use the search function. Once you open that, all of your drives should be displayed and all of the settings functions to rename and manage volumes and partitions are there using the toolbar or right-clicking on the appropriate drive. To change a drive letter, the letter has to be unoccupied. For example, if you want to make your HDD the D: drive, you have to rename or remove the current D:, approve the option to restart Windows (a pop-up window), then change your HDD name from F: to D:.