Yes, you can change the main domain name associated with your hosting account. For that, you can contact our Hosting Support team in live chat.
You will need to provide your current domain name and the one you would like to host as well as your hosting account information: NityGity account username, cPanel username, support PIN to verify your ownership.
Note that the domain name you would like to host should be registered. Content and email accounts will be re-assigned to the new domain name, and the previous one will be removed from the server.