I think you should handle this professionally and 1) quit in person, and 2) give them enough time to find someone new. It is completely okay for you to feel like the job is not for you. It IS hard, but would you rather do something you hate for a while or quit before they are completely reliant on you? Let them know, and while you find a job, allow them to replace you. It is a probation period for both you and your employer. The best thing to do, however, is to give them enough time, give your notice ahead of time, and don’t just disappear. That will burn bridges!

Leaving is the right thing to do for you and everyone else involved.
You know that’s what you want to do, and you can’t be happy while living against your own desires – this I have learnt the hard way.
I’m still stuck in the wrong career at 24 and have spent years in the wrong jobs.

Don’t waste your time.
It’s like a relationship really … If you act like you still love this job (though maybe you did), you’ll just hurt them more when you leave later. Or something like that.

They’ll be fine without you, and if they’re not… it’s not your problem and there are frankly much bigger issues at play in this crazy World.

Don’t worry about it. And they can’t be angry at you if you politely explain this isn’t where you see yourself in the future.

If they don’t understand, that’s there problem.
Do what you want.

YOLO.