Hi! I'm Eric, a networking pro who's been paired with you through JustAnswer.com. I'm reviewing your question now, and will return w/ an answer soon!
Given that this server was just installed and you've no clients authenticating against it, you should run into no trouble removing the CA and reassigning this server to your domain.
To remove the certification authority:
Click Start, point to Administrative Tools, and click Server Manager.
Under Roles Summary, click Remove Roles to start the Remove Roles Wizard. Click Next.
Clear the Active Directory Certificate Services check box, and click Next.
On the Confirm Removal Options page, review the information, and then click Remove.
If Internet Information Services (IIS) is running and you are prompted to stop the service before proceeding with the uninstall process, click OK.
After the Remove Roles Wizard is finished, you must restart the server to complete the uninstall process.
Afterward, you can re-attempt to join the server to your domain and should experience no further trouble.
Thanks for your question! Please do let me know if I may be of any further assistance.
Yes, please do! I don't anticipate you'll run into any issues at all, but would certainly like to know how it works out. If, by chance, you do run into something unexpected I'll be glad to assist further.
Hi again! It's been awhile since we chatted...I was curious if you were able to resolve your "certification authority" issue?
Thanks...I look forward to hearing from you!