If your goal is to format the C: drive—the drive where Windows Vista lives—you cannot do this while Windows is running. It’s like trying to wash a car while you are sitting inside it; you can't clean the seat you are sitting on.
“I have to format,” he muttered, rubbing his temples. windows vista format hard drive
If you're unable to access Disk Management or prefer to use the Windows Vista installation disc, you can format the hard drive during the installation process. Here's how: If your goal is to format the C: