CBSE has announced the JEE Main photo correction and the signature correction window from December 8 onwards to rectify any mistakes made by candidates. 

If there will be any discrepancy in your image CBSE will send you the message related to it and then you can edit it. 

For other correction option will be available tentatively in second week of January.

You can change the following below options

1- Change in mode of exam: The candidate will be allowed to change the mode of exam from pen & paper to computer-based, but the reverse will not be allowed.

2- Aadhaar card details

3- Medium of exam

For more information you can refer below link

JEE Main Application Form Correction 2018

Good Luck!!