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Cynthiaom's avatar
Cynthiaom
Copper Contributor
Mar 13, 2026

How to completely reinstall windows 11 from usb for downgrade

Windows 11 25H2 but i don't like it. Some recent updates the system feels slower and some of my apps are not working properly. Because of this, I want to completely reinstall windows 11 from usb and ...
device management
Update management
GabrielMartinez's avatar
GabrielMartinez
Iron Contributor
Mar 13, 2026

There are a couple of things you should pay attention to when completely reinstalling Windows 11 from a USB drive.

Back Up Your Data First

The most critical step is ensuring all personal files, documents, photos, and browser bookmarks are safely copied to an external drive or cloud storage. A clean installation will erase everything on the system drive where Windows is currently installed. Verify the backup is accessible before proceeding to avoid permanent data loss.

Understand BIOS Settings and Boot Order

To start the installation from the USB drive, you must enter your computer's BIOS/UEFI settings (usually by pressing F2, Del, or F12 during startup) and change the boot order so the USB device is first. Furthermore, ensure that Secure Boot is enabled and that your SATA controller mode is set correctly (often AHCI) to match your hardware configuration, preventing installation errors.

Manage the Installation Process

During setup, when prompted for the installation type, choose "Custom: Install Windows only (advanced)." This allows you to delete, format, and manage the partitions on your drive. Be absolutely certain you select the correct drive/partition to install on to avoid accidentally wiping the wrong disk. After the automated setup completes, you will go through the out-of-box experience (OOBE) to configure your user account and settings.