Here is a detailed breakdown of how a clean install works, what stays, and what goes. Understanding the "Target Drive"
The partition you select will be wiped (or data moved to a Windows.old folder if you don't format) to make room for the new OS.
Choose the option when prompted.
If you want, tell me which OS installer you're using (Windows, macOS, Ubuntu, etc.) and whether you have multiple drives; I’ll give step-by-step instructions for a safe clean install in that environment.
During a clean install, the process typically targets only the "target drive" (usually labeled C:) where the operating system will reside.
Physically disconnecting secondary drives is one of the safest and most recommended practices for protecting your data during a clean installation. It eliminates any possibility of selecting the wrong drive.