You need to remove the following list below in order.
a) Remove each email account created on this domain
b) Remove mail domain
c) Remove website created on this domain
After removing the above, continue with steps below.
1. Login to SolidCP.
2. In the next screen, you will see icons for all the services you can manage from the SolidCP. To delete a new domain, under System section click Domains icon.
3. Select the domain that you want to delete.
4. Click the Delete button. Then click OK to confirm the process.