Hi there.

The correction window will be open from January 19 to January 31, 2019. During the correction window candidates won't be able to change their category, gender, nationality, State eligibility and Pwd status but surely be able to change other details. 

Hence, application forms can be further edited only during the correction window. And, as you can see that you cannot change your category now according to the strict guidelines being followed by the NTA I'd suggest you to call the authorities and ask them for clarifying the matter.

Hope this helps.

Give a suggestion that shall I want for the correction window or shall I refill the application....

You cannot correct the Category during the correction window as category affects merit list. But filling the wrong category and sitting for the exam with the same details after knowing the mistake is a malpractice. The NEET guidelines are strict about that. I would suggest you to fill up a new form with a different contact no#, Email and the right category details. What you might lose now is the cost of an application form. But if you attempt NEET, qualify and then get an admission under OBC NCL and you don't submit the certificates because you don't have them, it's illegal.