This Active Directory domain controller is a global catalog server. If you remove Active Directory Domain Services (AD DS) ...

This Active Directory domain controller is a global catalog server. If you remove Active Directory Domain Services (AD DS) from this computer, users might have trouble logging on to domains in the forest. Before continuing, ensure that enough global catalog servers are in this forest and site to service user logons. If necessary, designate another global catalog server and update clients and applications with the new information.

Do you want to continue removing AD DS from this computer?