Note the “reverse vesting” bit, this caught me out too. This is not the standard employee “you have zero until your 1yr cliff” deal, it’s the opposite in some sense, the founders own their shares unless they leave, in which case they are clawed back, and the clawed back amount goes by the 4yr period.

In this case if the investor has voting rights, neither founder has a controlling share, and the investor is the tiebreaker. So OP can fire the other founder with the investor’s vote.