sComputer 	= "SWYNKSRV01"	'-- name of the computer where SQL Server is installed
sSQLServer	= "SWYNKSRV01"	'-- name of the SQL server instance containing the database which log is to be truncated
sDb  		= "Northwind"	'-- name of the database which log is to be truncated

Set oInstance = GetObject("winmgmts:{impersonationLevel=impersonate}//" & _
		sComputer & "/root/MicrosoftSQLServer:MSSQL_TransactionLog.SQLServerName=" & _
		Chr(34) & sSQLServer & Chr(34) & ",Name=" & Chr(34) & sDb & Chr(34))

Set oOutParam = oInstance.Truncate()	

If oOutParam.ReturnValue = 0 Then
	WScript.Echo "Transaction log of the database " & sDbName & " truncated successfully"
Else
	WScript.Echo "Truncating transaction log of the database " & sDb & " failed with the error " & oOutParam.Description
End If