The log folder can always be cleared if you no longer need the information. It is worth seeing if you can fix the reported error in the log though (whatever it is) if you can to prevent reoccurence.
Please search forums before posting. Please make sure your post includes the version of the CMS you are using and a link to the problem. Annotations on screenshots can also be helpful to explain problems/goals. Please use the "secure" tab for confidential information.