This question about Legal Guardianship will help to determine if you are to be considered a dependent or independent student for Federal financial aid, specifically.
If you have a legal guardian who is not a biological parent and deemed as such by a court, then you will be considered “independent.” This means that you do not have to provide any biological parent (or guardian) information in your FAFSA, and may move along. Otherwise, even if you are over the age of 18, you are still considered a “dependent” student for Federal financial aid purposes. This will remain the case even if your relationship with your parent(s) is not intact.
You may want to contact your school’s financial aid office if your circumstance warrants such a condition that you may need to remove yourself from your parent’s custody.