Due to a design flaw up to OpsMgr SP1 a manually installed OpsMgr Agent could be remotely managed from the OpsMgr Console, even though it didn’t always give the expected results. So from the OpsMgr Console manually installed OpsMgr Agents could be repaired, uninstalled and moved to another Management Server.
However, in R2 this functionality has been repaired and manually installed Agent can not be remotely managed from the Console. Now the server/workstation with the manually installed OpsMgr Agent has to be used in order to change/repair/remove the OpsMgr Agent.
When running W2K08 with UAC enabled this cannot be done from the Control Panel. This blog posting of mine describes how to go about it.