If you have a need to completely blow away the Offline Files cache contents due to corruption, confusion or sheer frustration, the following steps will achieve this:
Navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\CSC
Create a new key and name it Parameters
Inside Parameters, create a new DWORD value; name it FormatDatabase
Give FormatDatabase a value of 0x1
Restart your computer.
Unlike Disable Offline Files in the Offline Files Control Panel applet, this process will completely wipe out any Offline Files and any offline changes you have made. This should be a change of last resort. Make sure you have a backup before you perform this action!