Hello aspirant
If you are talking about jee advanced then you cannot change your exam center now as iit delhi had closed the option to change examination city for jee advanced which was opened from September 16 to September 17 . As admit card of jee advanced had been released there is no any way to change exam city now you have to give your examination at alloted centre. You cana make 1 day prior visit to your centre for avoiding inconvenience.

You can get train ticket as governments is running special trains for students for exam or you can borrow some money for taking bus  in worst case

Hope this will help

Best of luck.

Hello,
Students were allowed to choose the exam centres for by choosing eight cities of their choice during the registration process for the exam.
Out of the 8 selected choices, students were allocated centers for the exam.The allotment of seats were done by the authorities and it cannot be changed now.
Please try to visit the exam city a day before the exam so as to make yourself familiar and have no confusion.

Hope it helps