Hey,
Your question is bit vague and incomplete.
If you have filled the form for Bachelor of Arts for any course,then also you can withdraw anytime.
And if you do not want to pursue then it is completely fine. In fact;it's good that you realised it before hand.
And there is no need to make any excuse. It's your life and it should be your decision. Talk to your parents. Try to convince them. Tell them the genuine reason and also share with them about your future plans.But,no matter what subject you choose to study,you will have to put in all the hardwork.
Hope this helps.
Good luck.