To clear an event log
Open Event Viewer
In the console tree, click the log you want to clear.
On the Action menu, click Clear all Events.
Click Yes to save the log before clearing it.
Click No to permanently discard the current event records and start recording new events.
To open Event Viewer, click Start, click Control Panel, click Performance and Maintenance, click Administrative Tools, and then double-click Event Viewer.
You must be logged on as an administrator or a member of the Administrators group to clear an event log.
After you clear a log, only new events will appear in the log.
If you select Do not overwrite events (clear log manually) in the Properties dialog box of an active log, you must periodically clear the log either when the log reaches a certain size or when a message notifies you that the log is full.
You cannot clear archived logs; instead, delete the archived log file.
Free an event log when it is full
Archive an event log
Open an archived event log
Event Viewer overview