When a system loses a role, eg. it is demoted from Domain Controller to member server, the logs associated with that role remain in the Event Viewer console on that system. This can be quite annoying, not to mention misleading. Not only is the category retained in Event Viewer, but all the events are there as well.
I will not show you how you can remove these logs. The problem is that the .evt files are locked and cannot be deteled. They are locked by the the Event Log Service which cannot be stopped. The solution is to use Mark Russinovich’s excellent utilities PendMoves and MoveFile. You can find them here:
Windows often needs to replace a file that is in use. This presents a problem when the process using the file cannot be stopped. To resolve this problem Windows has a spesial API that can tell Session Manager to delete that file, or replace it, on the next reboot. The MoveFile utility does just that. It tells Session Manager where to move, or delete, a file on the next reboot, before the system starts it’s services and applications. This info is stored in the registry key HKLMSystemCurrentControlSetControlSession ManagerPendingFileRenameOperations. You can write to this key using WMI or your own app, but I use Mark’s tool since it is already there.
To get rid of eg. the old File Replication Service Log from a server you would first go into Event Viewer and get the path to the .evt file by selecting properties on the log. Usually you would get C:WINDOWSSystem32configNtFrs.evt
Next, run the following command from the directory where you extracted PendMoves and MoveFile:
MoveFile.exe C:WINDOWSSystem32configNtFrs.evt “”
The “” indicates a NULL destination and is interpreted by Session Manager as a delete operation.
Now you can run PendMoves to get a list of any file move/delete operations scheduled for the next reboot.
But to get completely rid of the log we also will have to remove some setting in the registry, or else the Event Log Service would just recreate the file we deleted. The new file would be empty, of course, but the log would remain in Event Viewer.
Continuing the example with the File Replication Service Log, navigate to the key HKLMSYSTEMCurrentControlSerServicesEventlog
This is the main key for the Event Log Service and it has a subkey for each log that Event Viewer displays. Delete the entire key of the log you want to get rid of.
After the next reboot the logs should be gone from Event Viewer.
Sometimes they are not however. This usually happens because the service that uses the log is still set to Automatic startup. For example; when a DC is demoted to member server, the FRS service is not stopped and disabled. If this is the case the registry key you deleted will be recreated by FRS at startup and a new logfile created. So make sure to check all corresponding services before rebooting.