What should I do when I want to leave my family and join another at 16-years old?

It would be inappropriate for anyone to say- go ahead, or don't go ahead, without any information on the circumstances.

Why do you feel the need to leave your parents, at age 16.

Yes, please supply more information and background such as why there are no parents in the other 'family' and the age of the oldest child as well as why you think it would be an appropriate move.

We all get angry with our parents over things, but most people don't consider moving out.

Provide some details. Are they abusive? Neglectful? Drunks? Drug addicts?

You should realise that you can't, it is not legal and proper to merely leave your family, even if the state removed you from your home, most likely that is not where you would go

You put those thought out of your head as being silly and immature.