Hello dear aspirant

As you have already appeared in NCHMCT JEE 2020 on August 29 with your category as general while filling the application form, you cannot sit in counselling with an EWS certificate. This is so because when NCHMCT JEE cutoff will be released, it is different for each category. General candidates have different cutoff and EWS category has a different cutoff.

However you can still take your EWS certificate and ask the query desk of NTA or ant NCHMCT JEE score accepting college if you can use it in counselling.

For detailed explanation on NCHMCT JEE cutoff, check the link below:

https://hospitality.careers360.com/articles/nchmct-jee-cutoff

No you can't do that.. Once the category which has been filled by you remains throughout. So you can't change it. For more reference you can check the JEE website.. It has been clearly mentioned there.