[notauser]

Sure, if you hold 51% of the equity, and even then it would get messy.

The power to hire and fire is (usually) the CEOs, devolved from the board. The board is (usually) appointed by the equity holders.

For some set ups reversing a CEOs decision might require 50%+ of the shareholders deposing 50%+ of the board and replacing them with tame board members who fire the CEO and appoint someone else.

That's going to look pretty bad to the staff, any investors who don't agree, anyone you might try and hire as the new CEO, customers and any potential future investors. And after all of those people have run away as fast as they can how much of a company is really left?

[slapshot]

In many venture-backed companies, the Series A (and B, C, ...) shareholders are guaranteed a certain number of board seats--solely by virtue of holding preferred stock. The founders (who hold common stock) have no control over how the preferred shareholders use their board seats.

If the preferred shareholders have an outright majority on the board, it's black and white that they can effectively fire the founders.