You have confused yourself a little. The 84.6Gb is the total content of the ....\local directory which is actually itself containing no less than 217 sub-directories. These are working directories and installation files of all the applications you have installed, and few of them can be truly called 'temporary'. It's true most of them will never be needed again, but it would be risky to delete them all, as you can have no idea what most of them are.
I recommend using the built-in disk cleanup tool. I dont know where it is in Windows 8.1, but in Win 7 it is control panel / performance information and tools / open disk cleanup. Try just press windows button and key disk cleanup.
You could also download a nice little tool like 'Treesize free' and start it from ...\local to see if there is one sub-directory with massively excessive space used. Typically it will turn out your anti-virus is quite needlessly storing all the virus signatures downloaded this year, or your internet connection is keeping all it's logs, or you have many crash dumps, or......all sorts of rubbish actually. A modest target for 'local' space would be less than 5Gb
