It is going to be pretty tough to homeschool without your parents approval. In most states you cannot just leave school, you have to show the state that you are actually being educated, and your parents have to do the paperwork.
If you want to show your parents that there are options, you should start by investigating the rules for your state. While homeschooling is legal in all 50 states, each has their own regulations.
Why not start by telling us which state you are in and maybe someone from that state will chime in with info.