Availability Group - Deleting old backup files
Since you mentioned this is in an AG, are you sure you're running the command and checking the backup folder on the same server?

If you are connecting to the Availability Group primary through the AG listener, then running the xp_delete_file command will run on whichever physical server happens to be the primary replica at that time.

Try running SELECT @@SERVERNAME to verify which server you're connected to when you run the backup deletion command, then check that server's F:\ drive to see if backups were deleted or not.  

You should also verify that you are getting a 0 as the return code from the extended stored procedure:

DECLARE @ReturnCode int;
EXECUTE @ReturnCode = [master].[dbo].xp_delete_file 0, @BackupDir, 'bak', @Date, 1;
IF @ReturnCode &lt;&gt; 0 PRINT @ReturnCode;


Note that the example call to xp_delete_file you provided is targeting files with a .bak extension.  The example call to Ola's backup script is targeting log backups, which will have an extension of .trn by default.  This may be contributing to the discrepancy you're seeing.



By the way, I would strongly recommend that you take backups to somewhere other than the local drive.  Not only does it represent a single point of failure for your SQL Server instance and critical database backups, but it can actually be pretty confusing with an AG when doing restores.

In particular, if your transaction log backups are being taken to two different locations (local folders on each replica), restoring to a point in time over a period that includes an AG failover will be tough.  You'll have to get the log files from both servers and make sure they get restored in the right order.  The process is much simpler if they all go to a network location like \\servername\backups\MyAgListenerName\DatabaseName\LOG.