You can always change the main domain associated with your domain space from domain settings.
When main domain is changed, you have to again verify domain, re-publish sub-pages for the changes to take effect
1 First step is to make sure you are in the right domain space or navigate to the domain space to which you want to access.
2 Then Click 'Domain Settings' from your SubPage domain space dashboard.
3 The domain settings opens up and under 'Change Domain' you can enter the new domain and click save.
Make sure you enter your main domain Example: mybusiness.com ✅ and not your subdomain here like sub.mybusiness.com ❌