You can’t format the hard disk on which Windows is stored while Windows is running, for the same reasons that you can’t work on a car’s engine while you’re driving it. To format the primary drive - the hard disk where the operating system resides, also called C drive or C: - you need to boot into the setup program on Windows 7 or Windows 10 and use it to format your drive. The following steps show you how to format your primary drive when all applications and your files are gone. Then you can use the Windows setup program or macOS Recovery Environment to format primary hard drives. You may need to reinstall the operating system, but you don‘t want to lose your data! If it’s at all possible, begin by backing up and rescuing everything of importance, or clone your hard drive by using one of our guides: How to clone a hard drive. How to Format a Hard Drive on Windows or Mac | Avast Logo Ameba Icon Security Icon Security White Icon Privacy Icon Performance Icon Privacy Icon Security Icon Performance Icons/45/01 Security/Other-Threats Icons / 32 / Bloatware removal Icons / 32 / Registry Cleaner Icons / 32 / CleanUp Icons / Feature / 32 / Mac Icons / 32 / Browser cleanup Icons/32/01 Security/Malware Icons/32/01 Security/Viruses Icons/32/01 Security/Other-Threats Icons/32/01 Security/Passwords Icons/32/01 Security/Ransomware Icons/32/01 Security/Business Icons/32/02 Privacy/Browser Icons/32/02 Privacy/IP adress Icons/32/02 Privacy/VPN Icons/32/02 Privacy/Proxy Icons/32/02 Privacy/Streaming Icons/32/03 Performance/Celaning Icons/32/03 Performance/Drivers Icons/32/03 Performance/Gaming Icons/32/03 Performance/Hardware Icons/32/03 Performance/Speed Icons / 32 / Bloatware removal Icons / 32 / Registry Cleaner Win Icons / 32 / CleanUp Icons / Feature / 32 / Mac Icons / 32 / Browser cleanup Icons/60/02 Privacy/02_Privacy Icons/60/01 Security/01_Security Icons/60/03 Performance/03_Performance Icons/80/01 Security/IoT Icons/80/01 Security/Malware Icons/80/01 Security/Passwords Icons/80/01 Security/Ransomware Icons/80/01 Security/Viruses Icons/80/01 Security/Other-Threats Icons/80/03 Security/Business Icons/80/02 Privacy/Browser Icons/80/02 Privacy/IP adress Icons/80/02 Privacy/VPN Icons/80/02 Privacy/Proxy Icons/80/02 Privacy/Streaming Icons/80/03 Performance/Celaning Icons/80/03 Performance/Drivers Icons/80/03 Performance/Gaming Icons/80/03 Performance/Hardware Icons/80/03 Performance/Speed Icons/80/03 Performance/03_Performance Icons/80/02 Privacy/02_Privacy

Usb you need to format the disk