Hey,

Different Universities have their policies whether they will allow you to change the stream or not. However, if we talk on a general viewpoint, you have the possibility to change the stream from Civil Engineering to Computer Science Engineering. But, in most of the case you need to start from beginning and clear your concepts in the field you are actually interested. To be more clear, you can ask about this to your concerned department, university authorities to get more clarity regarding the situation.

Hope it helps