My recommendation is to use first the Windows specific Disk cleanup tool, see  [URL]  With it you can also select to clean up the old windows version files, if you do not plan to revert to a previous version or build of Windows 10. After that cleanup also the SupportAssist cleaning is much faster. I am personally against using cleanup tools different from the Windows ones, the risk is always high that files used by Windows are deleted by mistake. Last week, after a SupportAssist run on a XPS 13 9360 that we have at home , the list of the Windows installed updates also disappeared. Not a big issue, but this was not expected ! - Note: I am a Dell user     
Hi, I am using supportAssist 3.1. it takes too much time in clean files. and I cant skip it. Please help me. 
SupportAssisst Takes Too Much Time In Clean Files