Set-CsDeviceUpdateConfiguration, the forgotten command of many a Lync/Skype project. If you don’t want the LyncShare\x-WebServices-x\DeviceUpdateLogs\Server\Audit\imageUpdates folder filling up beyond what is deemed necessary, then use the following:
Set-CsDeviceUpdateConfiguration -LogCleanUpTimeOfDay 17:05
You can also modify the retention time with the -LogCleanUpInterval 5.00:00:00 for a 5 day retention or 365.00:00:00 for 1 year. Default is 10 days, but unless the time of day is set, the process will never kick in.
Try not to set it 5 mins ahead, or you might be waiting 24 hours and 5 minutes for it to actually start deleting, a good Microsoft Minute (15 mins) should do, or just schedule, check the next day that it’s working and cross it off your monthly/quarterly maintenance check list.
Technet article: https://technet.microsoft.com/en-us/library/gg398320.aspx