Just had a look in that folder and the file "aswAr1.log" is just for today on my system, it's the anti-rootkit log and I suspect if it's deleted it would immediately grow right back to the same size.
If you want more control over the log sizes go into "Settings->Maintenance":
Thank you, Andavari, I've limited the size of the Log Files, so shall see what happens. Yes, oops, you're right about "aswAr1.log", it's the other two that keep growing.