Stop logging all successful backups in SQL Server error logs

sp_cycle_errorlog

BACKUP DATABASE [D1] 
TO DISK = N'C:\Temp\D1.bak' WITH NOFORMAT, INIT
GO

DBCC TRACEON (3226,-1)

BACKUP DATABASE [D1] 
TO DISK = N'C:\Temp\D1.bak' WITH NOFORMAT, INIT
GO

DBCC TRACEOFF (3226,-1)

BACKUP DATABASE [D1] 
TO DISK = N'C:\Temp\D1.bak' WITH NOFORMAT, INIT
GO

Permanent solution: