I want to leave the system and live independently, but I'm 15. Is that a possibility or do I have to wait until 16 to be independent

Where do you live? You might have to wait until you are 18.

Are you in school? Do you have a full-time job?

Right and if you are in CA it may not happen until you are 21.

It depends on where you are going. If you are in foster care and have no parent(s) or guardian(s) to go to, it is highly unlikely. You would need to speak to a social worker or lawyer.

Depending on why you are in foster care you MAY have to stay in until you are 18.