Think about what you wish to do if you were you quit gaming and you have found yourself a great reason to quit.
If you really are determined to quit gaming, you may need a reason, because people don't do stuff if there is no reason for it: the best one I could think of is that gaming takes up precious time that you're not getting back: time that you could use to learn something and better yourself.
While gaming does not offer great benefits, there are hobbies that do and others that don't, for example, there's this Youtube channel called Linus Tech Tips that teaches you about all sorts of hardware. You could spend all of your waking time studying to be the very best in your class or to learn a subject you're passionate about.
In my opinion, it would be good to set yourself to a mindset of gaming is only a hobby and go from there: it could help quitting if you tell yourself gaming is a secondary part of your day, because it is. Consider investing more time into your main projects and priorities while keeping gaming to a tiny amount. There's nothing wrong with playing just a little bit.
Instead of quitting completely, you could use gaming as a mean to lay off the stress from school, work, and your main goal, but that's about it.
If you can work the self-control, set a timer for a few hours a day and decrease it from time to time.