I want to tell my sister to be more tidy when she comes to visit me
Why do you want to call her out for not being neat?
Her dirty panties are scattered all over my room behind the desk.
I understand your need to talk to her. You'd think she would know this at her age and be more respectful of your home.
I think she's just trying to get me pissed off and I am going to kick her out for good.
Making your sister leave your home, just because she isn't as neat as you would like is a bit overkill as a response to the situation. Try talking to your sister first before you take extreme measures.