Quitting RuneScape really isn't that hard. I mean, myself, I came back a month ago, played it for a few days and haven't played a legit second of the game after that, I've only botted. Just think really hard, just take a few minutes to think, why you actually play the game. If you think that you have a good enough reason to keep playing you do that. But in reality, there is no good enough reason, because all in all its just a pixelated game eating at your brain and the rest of your life. I know you people might think I'm a hypocrit, but trust me, I can quit, anytime I like... This is just a hobby for me, I do this in my spare time, the sideline of my day to day life. School/friends/socialization comes first, then RuneScape/Sythe etc.
If you really want to quit then do what I said, and have a think about why your really playing the game.