If you're trying to reform, you might be looking at it the wrong way.
In my job, I get to understand humans at a very raw level, what drives us, what makes us who we are and why we do the things we do. While I've never had the direct job of exploring why people are very, very toxic in a game and I mean that kind of toxic where your favorite sentence starts with "k" and for some reason you keep mentioning certain, well-known diseases, I've had the opportunity to explore much else and extrapolation could be done.
In short, to anyone that's seriously consider to "reform", as in, to better yourself or change yourself: don't. It'll be anticlimatic and you're bound to enter an infinite loop.
It is my belief and I've seen people turn around that if you exhibit extremely toxic behaviors to the point of getting multiple accounts banned and I mean for the worst stuff, not just being negative, that you most likely don't excel at any (or all) of these areas in your real life: money (safety) , career (safety), social status (esteem).
These 3 pieces are heavily connected to Maslow's hierarchy of needs as shown by the parenthesis. Your needs importance (although food is more important than, say, status) is constantly updated by how satisfied the other needs are, for example, although, at a base level our physiological needs are the most important, most people living in the western world have them satisfied where as an african child will not - the pyramid is different in terms of what's more important. All of this means that you enter a constant state of existential stress, the end-result: you give in to your instincts easily. Because humans have egos, anyone who disagrees with them, even if they will claim that they are open to criticism and "learners", nobody really is, will be shown the door. Humans don't like to be made to think they are not the main character.
Take all of that and give people supposed anonymity and what happens is an unchaining of the ego ("Ego Unchained", lmao). The contrast is that the more your needs are satisfied, or rather you believe they are, even if you're lying to yourself, the less likely you are to give in to instinct and react the way some extreme people do.
We all have these thoughts, but we choose not to give in -- almost exclusively because our needs are met and we don't care about engaging in these behaviors that are so raw.
As such, trying to suppress your behaviors in an artificial way will never work and even if, say, you manage not to get banned on your new account, the stress is still there and eventually you snap back, you lash out somewhere. It might not be in League, but somewhere, you'll be searching for that release.
First: fix whatever is in your life that's going wrong. It's the only way.
Second: only spend as much money as you're willing to lose when you eventually get banned again.
I was perma-banned myself and looking back, I was trying to make it even bigger in my life at the time and I was extremely stressed. This meant I had no patience for others and this translated into me saying different things in my games that I'm not proud but they weren't the worst. Now I mostly complain because now I don't have time to play as much as I did before and when something wrong happens, it irks me that my short free time was wasted. It all comes from something else. It's not League itself, although the system seems to have been built to maximize tilt potential, but you. This is not to agree with everyone that's said "it's you, not your team" because that's just sugar talk used by people with an agenda but rather to recognize that your complex behaviors are rippled from very raw places.
Good luck.