How to handle leaving after a year-18 months at a small firm?

I joined a small single-manager L/S equity HF in NYC after graduation last year. The place is small (10 people), so I've had a lot of chances to learn and plenty to challenge myself with. However, being at a small place, I've become aware that all investment decisions will always go through the sole PM, and the chances of me getting to make any calls aren't likely at all. In addition, I'm not very interested in finance (or investing at least), and really just took the job out of college because it was different, paid well, and I wanted to work in New York. Graduated in 2016 from an Ivy with a STEM degree.

I've already spent over a year here, and will be coming up on my 18-month mark towards the new year. I've saved up a substantial amount of money through work and school (>$60k so far) and have no desire to stay in finance - but at the same time I am very appreciative of my employer for teaching me and giving me my first job. Since the office is so small, I know the politics and protocol are different than if I was to quit a large bank, but what is the best way to handle this? I want to be professional, but at the same time not waste any of my time doing something I don't want to do.

Thank you everyone in advance.