At some point, you may decide to remove a role that you no longer need. Removing a role in the past was error prone because you couldn't be sure you had removed all the component parts. Windows Server 2008 improves on this process through the Remove Roles Wizard.
You still have access to the Add or Remove Programs applet, as you did in the past, in Windows Server 2008. However, Microsoft has changed the name of this feature to Programs and Features. It's still possible to add or remove roles using this approach. Server Manager provides another option that you might want to try, however: Adding and removing roles can now rely on a wizard that helps you create a complete role rather than install a particular piece of software and find that you didn't install enough.
A server on a network - standalone or member - can function in a number of roles. As the needs of your computing environment change, you may want to change the role of a server. By using the Server Manager and the Add Roles Wizard, you can install Active Directory Domain Servers to promote a member server to a domain controller, or you can install individual roles or combinations of various roles, such as DHCP, WINS, and DNS.