OK, the AppData\Roaming
folder definitely should not
(and probably can't) be deleted as it typically contains settings, temporary and cache files for many of your installed applications.
In fact, once you look inside this folder you'll see more folders with familiar-sounding names (Adobe, Microsoft, ImgBurn, Mozilla, Skype, TrueCrypt, Winamp, to name a few examples taken from my own Roaming folder).
If yours is taking up 35GB then that's because some particular application is storing a huge amount of stuff in there that it shouldn't be. You might browse around a bit and find out which one it is, then we can see why there's so much data in it, if it's safe to delete it, or if we can move it to another location permanently.