WSS FAQ how to remove or disable Windows Certificate Authority (CA) role

How to decommission a Windows enterprise certification authority and remove all related objects
https://support.microsoft.com/en-us/kb/889250

Reinstall the CA role in Windows Server 2012 Essentials
https://support.microsoft.com/en-us/kb/2795825

How to Decommission a Windows Enterprise Certification Authority and How to Remove All Related Objects
http://social.technet.microsoft.com/wiki/contents/articles/3527.how-to-decommission-a-windows-enterprise-certification-authority-and-how-to-remove-all-related-objects.aspx

How to remove Active Directory Domain from Windows Server 2012 Essentials (bad idea), attempt to restore the simplicity of Workgroup (failed)
https://tinkertry.com/ws2012e-domain-removal