Hello,
If you dont want to continue in commerce field, they you can quit it. But if you take another stream then you need to study from first year onwards again,so think about it.
And some of the streams you can opt are
PCM
PCB
CEC
HEC...
but you are not interested in commerce because of toughness, then better don't take PCM and PCB.
ALL THE BEST !!
For any further queries you can ask me.

Science mat le bhai..gand ghis jayega