Not having a problem with Windows Server 2012 R2?
Windows Server 2012 R2 has several mechanisms to automatically cleanup previous versions of Windows Update files and uses compression for unused binaries.
If on win2k8 or win2k8R2, this will continue to grow as the OS ages and patches continue to be released.
Cleanup OS = Win2k8R2
Easiest - start with the Disk Cleanup wizard
Download and run this PowerShell script from TechNet Gallery
WinSxS is huge on win2k8R2, and the
Start with what's in C:\Windows\SoftwareDistribution\Download)
Delete logs, everywhere. Keep the most recent, but delete or backup any older logs.
SharePoint logs: C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\LOGS
Windows Event logs
Delete Internet Explorer's browsing history
Clean up Temp directory
Do you have SQL on the SharePoint Server? if so, do backups or otherwise compact the databases.
Reduce the size of your Windows swap file.
Optionally move to another disk like d:
Delete installation files can be downloaded again when needed. (check your downloads folder)
Clean up WinSxS folder https://technet.microsoft.com/en-us/library/Dn251565.aspx
Configure Diagnostic Logging in SharePoint https://technet.microsoft.com/en-us/library/ee748619(v=office.14).aspx?ranMID=24542&ranEAID=TnL5HPStwNw&ranSiteID=TnL5HPStwNw-8bUDdCvIXBhE7RsUncKgCw&tduid=(988dd788212d36221791baa597407ab9)(256380)(2459594)(TnL5HPStwNw-8bUDdCvIXBhE7RsUncKgCw)()
Configure diagnostic logging https://technet.microsoft.com/en-us/library/ee748619(v=office.14).aspx