forfiles /P C:\Windows\ServiceProfiles\LocalService\AppData\Local /M FontCache* /D -30 /C "cmd /c del @path"
From https://social.technet.microsoft.com/Forums/windows/en-US/3795364f-b66c-43ae-82d3-8ed5eb1aa2ce/local-service-system-profile-grown-to-extremely-large-size?forum=winserverTS