Forcibly taking away the phone and then being surprised by the aggression is pretty counterproductive. Your 14-year-old's brain is still developing and these platforms were literally designed to create addiction - it's not laziness on his part or a character flaw. When you cut him off abruptly, it's like unplugging something that was emotionally charging him, and of course he gets furious.
What actually makes a difference is finding an agreement where he feels heard. Ask him genuinely what attracts him so much - is it because all his friends are there? Because he feels validated by likes? Because it's a way to escape from something? The answers will be revealing. Then, instead of banning it, you work out limits together that make sense: no phone at the table is acceptable, but in exchange he has space to be online at other times. The goal isn't to control him, it's for him to realize he can manage this on his own.
It also helps a lot if you offer real alternatives - it's not just "stop being on Instagram," it's "let's do something that's also stimulating." It could be anything from going to the cinema to a hobby he's interested in. The irritability you're seeing is a symptom that he needs connection and validation; if you can channel it toward something else while gradually reducing screen time, it becomes less of a daily battle. This takes time, but it works better than impositions.