I'm going to ignore my little sister until she's an adult.
That's odd. What makes you want to ignore her until then?
She's really annoying.
Little sisters can be annoying, but it's not really feasible to ignore her for years. Even if you could do it, it would just make everyone miserable, including your parents.
But I hate talking to her.
I understand that, but ignoring her for year and year isn't going to make things better. Maybe you could try being nice to her, so then she'll be nice to you as well.