In recent years, Apple has made it increasingly difficult to completely disable Wi-Fi and Bluetooth on iPhone and iPad.
The reason for this is that Apple wants to make it easy to establish wireless communication with Apple Watch and AirDrop. So if you turn it off in the Control Center, Bluetooth or WLan will only be "disconnected" for paired networks or devices.
But the wireless connections remain active! As already mentioned for other functions such as AirDrop, Apple Watch or personal hotspot.
If you really want to switch off both W-Lan and Bluetooth completely on the iPhone and iPad, you have to proceed as follows and deactivate the options in the settings instead of the Control Center:
Instructions to completely disable W-Lan and Bluetooth on iPhone & iPad
1. Open the iOS
2. Navigate to "Bluetooth" or "Wi-Fi".
3. Manually turn off the function using the slider at the top.
This will now completely disable W-Lan or Bluetooth so that the wireless connection is really terminated.
You now know how to completely disable W-Lan and Bluetooth on iPhone.