If you are using your Raspberry Pi and you don’t need to use the Wi-Fi and Bluetooth like for example if you use it as a desktop or a server, it is recommended to disable it.

Note this disable the interfaces at the hardware level, not software, so it is disabled until you remove the config and reboot the Raspberry Pi.

# For Ubuntu 22.04, and any other distro that doesn’t have usercfg.txt:

1. Open the config.txt file located on the boot partition. (/boot/firmware/config.txt inside Raspberry Pi or D:\config.txt (drive letter might be different) in Windows.)
2. Add dtoverlay=disable-wifi below the bottommost [all] to disable Wi-Fi.
3. Add dtoverlay=disable-bt below the bottommost [all] to disable Bluetooth.
4. Save and reboot your Raspberry Pi.

# For Ubuntu 20.04, and any other distro that have usercfg.txt:

1. Open the usercfg.txt file located on the boot partition. (/boot/firmware/usercfg.txt inside Raspberry Pi or D:\usercfg.txt (drive letter might be different) in Windows.)
2. Add dtoverlay=disable-wifi to disable Wi-Fi.
3. Add dtoverlay=disable-bt to disable Bluetooth.
4. Save and reboot your Raspberry Pi.

# For Raspberry Pi OS (formerly Raspbian):

1. Open the config.txt file located on the boot partition. (/boot/config.txt inside Raspberry Pi or D:\config.txt (drive letter might be different) in Windows.)
2. Add dtoverlay=disable-wifi under [all] to disable Wi-Fi.
3. Add dtoverlay=disable-bt under [all] to disable Bluetooth.
4. Save and reboot your Raspberry Pi.

To enable it again just remove dtoverlay=disable-wifi & dtoverlay=disable-bt in your configuration and reboot.

Tested on Raspberry Pi 4 Model B.