In any Linux, Cloud or Windows hosting package, primary domain name is used as the unique identifier. Therefore the username is generated with a part of the primary domain name and its also used as the prefix for your databases/database users as well. In addition to that, primary domain name is used for the billing records and to manage some specific client area and billing handlers related to your service. Due to these concerns, it creates multiple complications to change primary domain name of a hosting package.
Therefore, no user is allowed to change the primary domain name of a hosting package.
What can I do if I was to use another domain name?
If you want to add another domain name you can simply add it as an "Addon Domain" name or a "Domain Alias" without changing the primary domain name. If you do not want your primary domain name, you can simply cancel it; but keep using your hosting package with an Addon Domain name or a Domain Alias. It's not mandatory to keep your primary domain name active in order to keep using your hosting package.
What can I do if I mistakenly entered an incorrect domain name when I placed my order?
If your hosting package is new (within 5 days after the activation), you can open a ticket to our Sales/Billing Department and we will try to assist you on this. However, please note that we will have to terminate the existing account with the incorrect domain; and freshly create it again with the correct domain name.