Open Administrative Tools – Internet Information Services (IIS) Manager, browse through Sites and select the WSUS Administration site and open Logging.
Second option is to completely disable logging, by choosing “Disable” on the Actions menu on the right.
The another way for controlling these logfiles is, in SBS 2011 there is by default a scheduled task configured that cleans the logfiles older than 100 days. The same task is added to SBS 2008 by installing Update Rollup 5 (KB2458094) only the default setting with this task is to delete the logfile older than 30 days.
The grown of the logfiles is caused by not closing the SBS console. My logfiles have shrunken to 20% of the original size with the console open whole day. There are 2 options to control the growth of these logfiles, IIS to disable logging or maximize the logfile size or the task added in sbs 2008 rollup 5 or sbs 2011 to control the maximum number of days logfiles are kept.