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.