Final answer:
To turn off Wi-Fi Assist on an iPhone, open the Settings app, go to Cellular, and toggle the switch next to Wi-Fi Assist to turn it off.
Step-by-step explanation:
To turn off Wi-Fi Assist on an iPhone, follow these steps:
Open the Settings app on your iPhone. Scroll down and tap on 'Cellular'. Scroll further down and locate 'Wi-Fi Assist'. Toggle the switch next to Wi-Fi Assist to turn it off.
Wi-Fi Assist is a feature on iPhones that automatically switches to cellular data when your Wi-Fi connection is weak. By turning it off, you can prevent your iPhone from using cellular data without your knowledge or consent.