How can you do to desactive the Fn key?

To disable the Fn key functionality, you can change the settings in your computer's BiOS or UEFI firmware. Restart your computer and enter the BiOS/UEFI setup (usually by pressing F2, Del, or Esc during boot). Look for an option related to "Function Key Behavior" or "Action Keys Mode," and set it to "Function Key" instead of "Multimedia Key." Save your changes and exit the BiOS/UEFI, and the Fn key will be deactivated for its default actions.