I'm a technical cofounder (with one other non-technical cofounder) of multiple years now. The company itself is still alive and kicking. Getting customers, evolving for product-market-fit, has runway, etc.
The problem is I don't want to work on this project anymore. It takes a lot of my time to be grinding out features for my cofounder, and I have a bunch of other ideas & pursuits that are more aligned with my career & life goals. I would be happier if I had time to pursue them in earnest.
But I'm not sure how to pull the plug. There are other engineers on the project, but I'm still who designed & built most of the system. I've also had a lot of input on product direction, in ways that I think have been important.
That said, my main skills are technical. But the company hasn't really required me to push my abilities lately, and the speed of the company isn't super dependent on engineering velocity anymore (we're way past MVP.)
Any tips? Or anecdotes of similar situations? Both for handling the quitting itself (and potential meltdown from my cofounder) and for now to do right by the company (and my investment.)
I have done the same as you are planning to do. I was also the CTO (and founder), while my cofounder was for the sales side. However my company was already more advanced I assume and I had already done a partial exit. I left after about 10 years of having founded the company, and don't regret it. Sure, I might not ring the bell later when we IPO, but I don't need this. That's just an ego thing, but that you have to accept :).
My cofounder didn't like so much that I was leaving, reasoning that the company would be worth less later, wouldn't grow so fast, or engineers or others employees would leave. I stayed another 1 year working 50% until I left completely (They still though tried to retain me later on, but I declined). At the end no one of the employees left, as they all understood why I was leaving.
Just talk to your cofounder and explain him why you are leaving. I assume if you haven't yet exited, and that he would request some parts of your shares to be given to a replacement CTO. I think this is fair. In my case, the replacement CTO was a internal engineer I hired 8 years ago, and I was free to leave already years before. At the end, a new person can also bring in new ideas, sometimes better, sometimes worse. And it's also great if employees see that they can progress in the company.
I still very much care though about my former company and still have lots of friends there (not just IT), and I'm still a large shareholder.