Here's the questions we thought through when our 3-person consulting firm split up:
https://ozar.me/2015/12/what-does-it-mean-to-buy-out-your-pa...
The first thing to do is read the startup's legal agreements. In our case, when we started the company, we agreed that partners (owners) could not participate in a business that competed with our own. You could leave at any time and do something competitive - but if you did, you thereby let go of your ownership. (You may also have a vesting schedule.)
If it's not obvious to you what your legal agreements mean, get a lawyer. Most lawyers will talk to you for 30 minutes for free to decide if it makes sense to hire them. Hiring a lawyer won't be cheap. You need the lawyer to tell you if you can simply walk away from the company and retain all of your ownership. If you can, then just ask the remaining partners, "What would you like to pay me to buy out my ownership?" It's simply a matter of what you're willing to accept.
Don't get hung up on valuing what the company will be worth in the future. If you can't agree on strategy, you won't agree on a valuation, either. Just ask them what they're willing to pay, and see if it lines up with what you'd accept. If it doesn't, and you can retain your ownership, and you believe the company will be worth a lot in the future, then walk away and keep your ownership.
But if you don't have that legal ability to keep your shares, then be prepared to accept a cup of coffee and a smile, and that's about it. (In our case, I bought out my cofounders because it was the right thing to do, but don't expect your partners to do the same. It's just a matter of character and your negotiation skills.)
https://ozar.me/2015/12/what-does-it-mean-to-buy-out-your-pa...
The first thing to do is read the startup's legal agreements. In our case, when we started the company, we agreed that partners (owners) could not participate in a business that competed with our own. You could leave at any time and do something competitive - but if you did, you thereby let go of your ownership. (You may also have a vesting schedule.)
If it's not obvious to you what your legal agreements mean, get a lawyer. Most lawyers will talk to you for 30 minutes for free to decide if it makes sense to hire them. Hiring a lawyer won't be cheap. You need the lawyer to tell you if you can simply walk away from the company and retain all of your ownership. If you can, then just ask the remaining partners, "What would you like to pay me to buy out my ownership?" It's simply a matter of what you're willing to accept.
Don't get hung up on valuing what the company will be worth in the future. If you can't agree on strategy, you won't agree on a valuation, either. Just ask them what they're willing to pay, and see if it lines up with what you'd accept. If it doesn't, and you can retain your ownership, and you believe the company will be worth a lot in the future, then walk away and keep your ownership.
But if you don't have that legal ability to keep your shares, then be prepared to accept a cup of coffee and a smile, and that's about it. (In our case, I bought out my cofounders because it was the right thing to do, but don't expect your partners to do the same. It's just a matter of character and your negotiation skills.)