"Mom, Dad, I want to be home schooled"
Do your research, find an acceptable home schooling curriculum. I'm sure that your school has info on it. Once you have all the info you need, tell them and present your findings.
how can i tell my parents out of no where without reason i want to be homeschooled?
Hippy is right. More and more parents are chosing to homeschool so you may get lucky.
Can I ask why?
There are other options and I personally feel Homeschooling is not socially healthy.
actually i went to home school before, its not as fun as you think! Maybe its depend on your parents way of parenting. My parent are not the hard, but my homeschool is as much as soldier camp! ( no kidding! Military school in my country has the same senior rules as my school! And they strong you cant do anythings against them!) in that day, all i have to do is 50% serving that guys! But i left for another school for high school so i didnt get the senior feeling.