SCCM The server cannot be deleted because it contains the following site system roles.
The server cannot be deleted because it contains the following site system roles Component server
How to resolve:
1) Make sure all the roles apart from Component Server and Site System are removed. You can check this by right clicking the server and checking its Properties.
2) Stop and restart the SMS_SITE_COMPONENT_MANAGER service. Wait for few minutes.
3) Refresh the console and the Component server role should now have disappeared. You should now be able to delete the server that holds the DP role.