Hi there. 

Any modifications in the application form submitted can only be done once the correction window is open. For neet 2019, correction window would be open from January 19 to January 31, 2019. 

During the correction window, students won't be able to change their Gender, category, nationality, State eligibility and Pwd status. Hence, as you have mentioned that you want to change category, unfortunately, it won't be possible according to the strict guidelines.

You can still call on the helpline number of NTA NEET to have more clarity on the matter. 

Hope this helps.

The authorities will provide the candidates with a definite amount of time or correction window after the NEET 2019 application process. During this time period provided, candidates can make changes to certain information in the application form. The correction window of NEET 2019 application form can also be utilized by the candidates to also make corrections (if required) to the already submitted information. The information submitted through the correction window will then be considered as final for the NEET application form 2019. So you can make changes