Easy. Uninstall. Just do it. Don't watch League on Twitch/YouTube or read League related discussions here or on Reddit. If you have friends who are also addicted to League and only know how to talk about it then you'll have to change the subject or limit the time you spend with them. First week or so will be tough but after the itch to play fades you'll feel like you can do anything. Then once you're done with your studies and other obligations for the day, find something else to occupy your free time with. You don't even have to quit video games entirely, there are many games that are enjoyable and aren't an addictive time sink with wild variations in the quality of matches that encourages you to keep playing more for adequate satisfaction. No matter how important you think grinding for meaningless internet points MMR is, it doesn't come anywhere close to the impact that having solid SAT/AP scores will have on your life in the near future. You have one shot to impress the universities, League isn't going anywhere and if you decide you want to hop back on the time wasting emotional rollercoaster that is League of Legends, it will be here waiting for you years from now.