I agree transaction log should be set up more often which i am looking into, but that should not stop the other maintenance plan to delete the old backup files.

I have double checked the extension it's BAK and not .BAK and it's TRN and not .TRN I have checked the path as well. That is fine as well. If i copy the path set up on Maintenance plan and paste it in explorer, i can see the back up files.