hi brother.

i assume that you are studying computer science and you want to change it to civil

if that is the case, then there are few options which Might help, but not definitely.

in case you are in the 1st semester and you want to change your department, then there is a possibility. any sem other than the 1st makes it impossible to change the department.

all polytechnic students study same syllabus untill 1st sem, so some college consider students who wants to change their department. but one and only if they have some vacancy in the required department.

if you are one such category then you can do this by requesting the college management. if not then there is only one other option. but it is a really risky one.

you have to quit you cs college and go with new admission with civil.

i hope the former becomes possible for you

feel free to ask any doubts in the comments.

good luck