Is it a sin to pick your lips and is it a sin to disobey your parents once you’ve grown up and moved out; what if their still your guardians?
No, picking your lips is not a sin. It’s just a habit which probably annoys you. Try rubbing a little hand lotion into your lips and avoiding too much chapstick, petroleum jelly etc.
Disobeying your parents is a wide category. If you are an adult capable of making adult decisions than you have a right and obligation to do so. Then not doing exactly as your parents say is not sinful. Again, the category is broad so no one can say for sure. If you give more details, it may be possible to get more input. Unless you are legally unable to care for yourself how can your parents be your gaurdians if you’re an adult?
Rule of thumb for whether something is a sin: do you intend to do it, do you know the full consequences ahead of time, are you intentionally turning away from God?
Christ’s peace be with you.
It’s for medical and financial reasons.