Usually, the change of stream can't be done after the 1st year because the course work for the BA & BSC courses are completely different. In Engineering courses it can be done, because the course for all the streams in the 1st year is the same. But for BA & BSc this is not the case. As a result, you can't to do so.

If you wish you can also contact your University, in order to know more about this.

I hope this helps. Wish you a great eve!