Hi Shaik, thanks for your query. 

You have not mentioned that about which exam you are asking about. I am giving answer based on counselling procedures of most of the exams. 

You can wait for other coming rounds where you can be alloted a different seat based on the choices filled by you. If there is no chance and you want admission in the same alloted college, then you should take it because syllabus in first year is same for all branches. You can change your branch in second year.

Best of Luck!