How to delete installsion cache created by hub on windows10

The unity just install caches on C disk without any configure pemission.
I know the system would delete automatically but only when install success.
I fail to install the first and get a information of "fail to delete installsion files..."so I decided to restart and reinstall.
But I still get the information
"fail to delete old installion files.Maybe unity or some of its tools are still runting."
I am sure nothing is runing except hub itself.
When it failes I just can not find and delete the caches.The C get a huge cosume of garbage files.
So anyone can tell me where the hub download the default cache files on C(win10)
I just neither can delete rubbish on c nor can install the unity.
The Hub is really a bad tool.

 

up and thanks