Formatting your hard drive is often necessary in order to prepare your hard disc drives for storing data. There is the Windows Disc Management tool for the easy reformatting any of the hard disc drives or removable storage devices like USB flash drives or a memory card.
Though without a boot disc or OS carrying CD ROM you cannot format the primary partition of your system where the OS is installed.
If you want to reformat your hard drive and do not have a bootable disc, then you can solve your problem in the following way:
By Configuring the BIOS
In this method, the first thing that you need to do is to get a Windows OS CD of any version that came after the 98 edition and insert it in your CD ROM. Then restart your PC and go to the BIOS to change the boot configuration. As your first booting device you need to select the CD ROM instead of your hard drive which is set by default. Save your changes and restart your system in order to exit from the BIOS.
Next time your system reboots, it will load from the optical drive and you need to properly follow the on-screen instructions. A list of all the hard drive partitions available in your system will be shown and you have to select each of them and press next when the system will ask you to format those partitions.
Choose any of the file systems and press next again. For every partition you need to repeat these steps. If you are going to use any operating system that came after Windows 98, you should prefer the NTFS file system. Once you are completed with all the steps, you have successfully completed your reformatting without a bootable disc and there will be no operating system in your PC too.
For Windows XP or Later Versions
If you are using Windows XP or any other post XP operating systems like the Windows Vista or the Windows 7, then reformatting any partition in which your OS is not installed is as easy as a matter of a few clicks. Select any of your hard drives and right click on it.
Choose the Format option from the context menu and in the following dialog box choose your settings and then click on the start button to start the reformatting. You can also select the type of file system from the dialog box that you will like to have for that partition.
You can always use different type file system for different partitions but the normal practice is to use the same file system for different partitions as it is considered to be more stable and less confusing for the operating system. The NTFS file system is normally preferred for hard disc drive partitions and for the removable USB storage devices like the flash drive or memory cards, Fat 32 is often the preferred file system.