Hello,

NTA website just opened some times ago so that's why some problem will occur. And this correction continue 27th January to 30th January 2021. So please don't panic and wait some moments. I hope form correction window also open soon and you can do it both together as well.

https://engineering.careers360.com/articles/jee-main-application-form-correction

Above link will guide you to correct the form.

All the best .