To find the folder location, you can just run the app, open the task manager (CTRL-SHIFT-ESC), select the app and right-click|Open file location.
else try here
On windows Vista and Windows 7, you will find the ClickOnce cache here: c:\users\username\AppData\Local\Apps\2.0\obfuscatedfoldername\obfuscatedfoldername
On Windows XP, you will find it here: C:\Documents and Settings\username\LocalSettings\Apps\2.0\obfuscatedfoldername\obfuscatedfoldername