[tech_nofounder]

  Respectfully, you sound like a fresh Alpha Male
  who's found a new pride, topped the old Alpha,
  and now you're looking to push him out entirely
  to cement your dominance.

I can see that it comes off that way. But the reality is, everyone seems to know this guy isn't hacking it, and I could tell almost immediately -- yet decided to do nothing for over half a year. For exactly that reason: I didn't want to risk the appearance of being an ego/power-maniac. But I'm now debating the wisdom of "just ignore it".

It's things that are borderline embarrassing (real example: not knowing what ssh is) in addition to just poor coding habits (breaking every style rule in the book), no systems instincts, and so on. Plainly, I don't think the CEO knew how to vet this guy.

[charlesdm]

Honestly, the only way to solve this is to be direct and ask him to leave the company. Bringing that up could go two ways; really good or really bad.

If he leaves then the company will probably have to buy back his equity stake, which will be expensive.

Also, don't forget, he probably has the power to fire you on the spot. These things do happen.

[jacquesm]

Nonsense. You don't crash a start-up on the say-so of an early hire.

A founder is a founder and barring actual misconduct or behavior that goes directly against the interest of the company should not be treated like he/she was a new hire, especially not by a new hire.