Have u tried not playing the game perhaps.
But on a real note, the best way to stop a bad habit or addiction in this case can be to simply keep accountability. If u can, ask someone like a friend or family member to keep you accountable in terms of not playing the game.
Another way is the 'out of sight, out of mind', where you get rid of the bad habit by keeping any and all triggers for that habit away. E.g. stop watching ur usual yt and watching something else like a show, getting rid of anything that reminds you of val/vlr. And generally try and get better habits to pass the time. Maybe pick up a book to read or a sport to play, maybe even some other game to play. Anything that can satiate the urge to play val, because most of the time you play because it's a habit to play, not because yoh really enjoy the activity.
Thirdly, to keep ur urges in check, it is be helpful to know that the urge to play val or do any other habits is attached to the space in which u do it. Most people subconsciously attach a specific activity to a space in their house usually, so changing ur deak to a different place or chaning ur setup might aid in stopping the urge for val.
Fourthly, try to keep as many obstacles in the way way playing val so that it's a chore to even to try play the game, like u can change ur password to ur riot account, try and get banned, uninstall riot client, etc.
Lastly, addicts lie to themselves all the time, so keep this in mind if u feel the urge to just play for a little bit like one dm or unrated, it's just a trick from ur mind to try and coerce you into playing the game. When this happens, try to do anything but play the game. Hell, you can even do some pushups whilst reminding urself that it's gonna be a waste of time, whatever helps you to not play really.
That's it, and good luck.