[greghinch]

This is why you have a board. And hopefully some decent legal documentation in place. Talk to them, lay out facts and the action you want to take, and just follow the documented process for things like board votes and such (again I hope you have legal docs in place, otherwise be prepared to get a lawyer and slog it out…). Sounds like you think the success of your company might depend on you getting rid of him, so just treat it like what it is: business, not personal.

[cma]

Majority shareholders can't just vote to take away equity from minority holders. There are laws about minority shareholder rights. The OP better have some really specific agreements in place.

[greghinch]

Well generally with more or less standard docs in place, the board can vote to remove the offending person from the company. And then it's just a matter of the vesting schedule as to the leaving person's remaining stake (this is why founders should have vesting). Not saying there won't be something of a legal battle, but certainly there's no special provisions necessary which you wouldn't expect in standard startup articles of incorporation.

[argonaut]

My impression is that in California boards have large latitude to extremely dilute minority holders.