Reason
Is a share permanently removed or offline that was previously used with the windows offline file cache (for example by roadwarriors) it can happen that you no longer can remove the cache with the windows ui.
Solution
All files changed and not previously synchronized and moved to the new location should be backed up or copied manually.
To reset and format the offline file cache two registry values have to be set (one for the used csc version, the other doesn’t harm)
reset_offlinefiles.reg
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\NetCache] "FormatDatabase"=dword:00000001 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Csc\Parameters] "FormatDatabase"=dword:00000001
Simply save this file and double click it to reset the offline file cache for the current logged in useraccount.
Another way is to use the REG.EXE program.
REG.EXE ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\NetCache" /v FormatDatabase /t REG_DWORD /d 1 /f REG.EXE ADD "HKLM\System\CurrentControlSet\Services\CSC\Parameters" /v FormatDatabase /t REG_DWORD /d 1 /f