The federal government assumes that parents will support their kids through college, so they look at parents' tax information, filed through the Free Application for Federal Student Aid (FAFSA), in order to determine how much financial aid a student needs. But an exception is made if a student meets one of 10 different criteria and is considered "independent" on the FAFSA.
Independent students give their own tax information to the government instead and, as a result, usually qualify for much more financial aid than dependent students who receive parental support. One such criterion for qualifying for FAFSA independence is being (or having been) an emancipated minor.
Emancipation laws vary state by state, but almost all involve a stringent process where the minor must prove that there's good reason to leave home. All this has to happen before age 18, the age of legal adulthood, so this option's success rate is slim but not nonexistent.