To remove an obsolete event log from being displayed in the Event Viewer follow the steps below.
1. Open Windows PowerShell with an account that has local admin permissions.
2. At the PowerShell command prompt enter: get-eventlog -list to list the event logs and make note of the event log you would like to delete. the name will be listed in the Log column.
3. To remove the obsolete event log, at the PowerShell prompt enter: remove-eventlog -logname <eventlog name>
Please refer to the attached screen capture named 'Remove Obsolete Event Logs' for an example of using the PowerShell cmdlets.