You don't get to choose whether you are a dependent or not. There are extensive rules that determine who is a dependent. To greatly simplify it, based on the few facts that you have provided, if you lived with your parents and did not provide more than half of your own support, you are their dependent. Being away at college counts as living with your parents.
Even if you are not a dependent, you still have to fill out Form 8615. Being a dependent is not one of the conditions that makes that form required. If you have enough income that you are required to file a tax return, your unearned income has to be reported somewhere, either on your own tax return or on your parents' tax return. Depending on the nature and amount of your unearned income, your parents might not be able to report it on their tax return. Even if they can, it's often a bad idea to do that because it can increase the overall amount of tax. If you have any income that cannot be reported on your parents return, and you are required to file a tax return, there is no way to avoid Form 8615.
Why do you not want to fill out Form 8615?
