How to correctly discard old backups?

I have an Execute SQL Task in my SSIS control flow that's backing up a number of databases before it proceeds to run the overnight ETL:

EXECUTE master.dbo.xp_create_subdir N'G:\Backups\DQ'
GO
EXECUTE master.dbo.xp_create_subdir N'G:\Backups\master'
GO
EXECUTE master.dbo.xp_create_subdir N'G:\Backups\Metadata'
GO
EXECUTE master.dbo.xp_create_subdir N'G:\Backups\NDS'
GO
EXECUTE master.dbo.xp_create_subdir N'G:\Backups\Staging'
GO
BACKUP DATABASE [DQ] TO  DISK = N'G:\Backups\DQ\DQ.bak' WITH  RETAINDAYS = 3, NOFORMAT, NOINIT,  NAME = N'DQ', SKIP, REWIND, NOUNLOAD,  STATS = 10
GO
BACKUP DATABASE [master] TO  DISK = N'G:\Backups\master\master.bak' WITH  RETAINDAYS = 3, NOFORMAT, NOINIT,  NAME = N'master', SKIP, REWIND, NOUNLOAD,  STATS = 10
GO
BACKUP DATABASE [Metadata] TO  DISK = N'G:\Backups\Metadata\Metadata.bak' WITH  RETAINDAYS = 3, NOFORMAT, NOINIT,  NAME = N'Metadata', SKIP, REWIND, NOUNLOAD,  STATS = 10
GO
BACKUP DATABASE [NDS] TO  DISK = N'G:\Backups\NDS\NDS.bak' WITH  RETAINDAYS = 3, NOFORMAT, NOINIT,  NAME = N'NDS', SKIP, REWIND, NOUNLOAD,  STATS = 10
GO
BACKUP DATABASE [Staging] TO  DISK = N'G:\Backups\Staging\Staging.bak' WITH  RETAINDAYS = 3, NOFORMAT, NOINIT,  NAME = N'Staging', SKIP, REWIND, NOUNLOAD,  STATS = 10

The intent is to only retain 3 days, and discard anything older.

The problem is that the .bak files just keep growing and growing for a week or two, until the G drive fills up and the Execute SQL Task fails, which aborts the overnight ETL.

It seems the .bak is apparently not discarding old backups; looks like I could go back all the way to the last time I deleted all the backups to free some disk space on that G drive:

The question is simple: it looks like my Execute SQL Task is doing it wrong. How do I fix it? Or is it something else?

My best recommendation for you is to use already applauded backup solution from Ola

CleanupTime

Specify the time, in hours, after which the backup files are deleted. If no time is specified, then no backup files are deleted.

I normally, use backup database ... with init and then delete the backup files older than X days.

Ola's solution is a one stop solution and its very flexible, so you can tune it as per your needs.

StackExchange Database Administrators Q#124354, answer score: 5