Douglas,

The standard MSIEXEC command to remove the agent by its product code should work fine. You can get theproduct code from the registry. FYI, it may require a reboot to complete the removal. In conjunction with agent removal, you may also want to remove its entries from the Reporting DB using Operations / Database Maintenance in the console. Un-installation of RCA Agent is also discussed in the Installation_Upgrade Manual, but I think the msiexec approach above is simpler than re-running setup.exe with parameters since it won't require re-deployment of the media.

if the client isn't being used, it won't likely be running a connect during the uninstall, which would have processes holding files open that would need to be killed.  Stopping the 3 client services before uninstalling should reduce the need for a restart.  (radexecd, radsched, radstgms)