A Fill or Kill (FOK) order is an order that is directed to be executed immediately at the market
or a specified price or canceled if not filled.
https://www.investopedia.com/terms/f/fok.asp
However, the point isn't whether the OP used a limit or FOK. It doesn't matter. It was about him sending and immediately cancelling large amounts of order which he never intended to execute in the first place. That's called spoofing.
Edit: One more note. Even if he sends FOK at market, if he sends an order much larger than what is being printed in the order book, it will not get filled because, by definition, you need to fill the entire order or it gets cancelled.