Hello dear student, 

Greetings! ! 

It totally depends upon the institution in which you are studying,  as some allows to change stream while some have strict rules which don't let students change their stream. 

But if you are not feeling good in your current stream , you must get it changed.  

I suggest you to ask about this to a your teacher or head of department , they may allow you to change your stream but he prepared to give them appropiate reasons for changing your stream. 

Thankyou