Hello there

Well you cannot change your category now since the admit card is released now .You cannot make any changes now .However changing category at the time of counselling depends totally on the institution .Some institutions may allow you to change your category if you are eligible and can produce the necessary documents ,other institutes might not be such helpful . But still you should go for counselling if your rank is good .

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-eligibility-criteria/amp

Best wishes