Working with event logs has become a lot easier in PowerShell v.2, and you have seen how you create and maintain your own logs. So, if you'd like to get rid of an event log, use Remove-Eventlog. But wait: this cmdlet removes any event log you specify, including pre-existing system logs. You should be careful what you delete because it cannot be undone. You will need Admin privileges to safeguard users.
Deleting Event Logs
Remove-EventLog 'Client Login Scripts'