Hello Karishma
The correction window is open now and yes you can change your category. Payment will be online and change will be considered only after successful payment before the given time. All the best. Please visit the link below for corrections

https://cbseneet.nic.in/cbseneet/online/CandidateLogin.aspx

Dear student

greetings

Yes, you can change your category when correction window gets open. CBSE this year provided 100% data correction facility for the benefit of children. the window will open from 15th March 2018 10 AM to 17th March 2018 11:50 PM. 

all the best.