but IMO in english the sentence make sense also without "only"
Not if you think about it. A tickbox with "delete files in windows temp folders older than 48 hours" implies that if you don't tick it then files older than 48 hours aren't deleted and that's wrong.
Not if you think about it. A tickbox with "delete files in windows temp folders older than 48 hours" implies that if you don't tick it then files older than 48 hours aren't deleted and that's wrong.