I'm also a lawyer and I know what it takes to create and maintain an LLC. It's a big fucking pain in the ass, and it is totally irrelevant to the success or failure of a business.
Maybe you can't see the view from your father's side of the equation. Nor can I -- I do not know you and we have never met. But I can guess what is going through his head.
What I do know is that I deeply want my children to succeed in life. I'll bet your father does, too.
I'll also bet that he doesn't give two fucks about owning 50% of a company with you. I'll bet in his eyes the company is 100% yours, and he wants nothing but the best for you.
He didn't invest in a company to buy you a MacBook. He gave you a MacBook because he's your dad and he loves you and he wants you to massively succeed in ways he never did.
He's watching you work hard, and I'll bet he is thrilled at every achievement, big and small. He's probably thrilled just to see you get down and grind hard. Do you know how rare that is in a 16-year old? That is gold to a dad.
He was probably crushed when you gave him the MacBook back. Because that meant you were quitting. I hate it when I see my kids quit. He doesn't care about getting his investment back. His investment is you. He loves you.
You had a company that you 100% owned. You quit. Your reason for quitting is because your father did not give you something you do not need. That's stupid on stilts.
Don't do that. If you quit now you will keep quitting when you are 18. And 22. And 30. And 45. And 60.
You published apps. That means you have a business. A business is one or more people producing something that other people (customers) think is valuable. They vote for your efforts by giving you money to show that they value what you produced.
You have a business. Don't throw that away.
You have a father who loves you. Don't throw that away, either.