You can destroy all the station and all ships by tracking them in all hostile (red if your are at war). Early alert and advanced radar technology can help you to intersept the moving fleets.

Once you destroyed all ship, pirates may buy a ship sometimes but nothing dangerous (AI companies pay a very small proportion amount of money that is share between company to help broke companies to survive).

However, a company is never removed from the diplomatie menu.

Thanks. I was confused because ships dont disappear from view even after theyre destroyed, and the ship count in the diplomacy screen doesnt update immediately.

It might be cool if companies could surrender; they could remain existing but youd get all their profits and theyd declare war/peace always aligned with you.

Yes, but as the companies can fight between themselves, it will be frustrating if all small companies disappear in early game to let to player only the biggest companies.
By keeping alive small companies, it provided to player small companies to fight with in early game.

You can always post ships at each shipyard and never declare peace ; )

@niavok yes i agree it's important to keep the balance, but later in the game, it would provide a goal to aim for. It's also kind of immersion-breaking when a company you reduced to 0 ships and bankruptcy will recover in only a few hours of playtime.

引用自 Niavok：

AI companies pay a very small proportion amount of money that is share between company to help broke companies to survive

Is this "free" money? In other words, if we were to bankrupt ALL AI, would they still get a trickle of income?

No, this money is not free. Each company pay 0.2% of its money to a money pool. And the pool is shared evenly between company. So if company don't have no money, there is no money to share.