Remove the drive's windows.
Remove the drive's windows.
You have an HDD with a Windows copy installed, and you're looking to free up space by removing the OS while retaining your files. You mentioned difficulty changing the boot order in BIOS. There are options to extract the Windows installation media or use tools like Rufus to create a bootable USB, allowing you to select the drive manually for booting.
You could remove every window file using File Explorer. It would be simpler to save the files you need, set up the drive, and then return them if you can.
If you're using Windows Vista or later, the typical folders people use are those inside your personal folder. Unless you have a reason to look elsewhere, it's usually enough. It's also important to consider whether any useful data exists there before deciding to remove it. At that stage, simply erasing it would be the best approach without concern. Who installed it—your own, a sibling, or a parent? You shouldn't assume any software will safely delete only Windows files; this process requires careful handling yourself.
I handled it myself. It was my dad's previous setup, focusing on the real Windows folder on Windows 10 with a total of 273,165 files amounting to 22.6GB. I'm sticking with windows.old and the related folders. Anything else named after Windows is now removed. All other files remain safe.
More precisely, it was the old family computer from about ten years ago when I was two years old. It might have taxes or other fees attached. Some programs could require payment and need to be retained. Overall, it's a chaotic setup, so I'm disabling Windows.
It was once upgraded. Review the folder: *:/Users/User_name/. The contents will show Pictures, Music, Videos, Desktop, etc. Most basic users keep personal files here. Windows.old might hold some remnants. You can check Program Files & Program Files (x86), though this usually only helps if you're trying to recover app data. There may also be information under %appdata%, but that’s less common unless you’re certain it’s stored there by default.
I handled the upgrade myself before we had an SSD ready. All files were in windows.old. Right now I'm just making it non-bootable until my dad checks it out and formats it later.