In order to delete a file, the file should not be in an open position. If a file is being used by another user, you cannot delete the file. If you are not having administrative privileges and if you are using a shared file, it may not be possible to remove files from folders. In such cases, you should consult your system administrator. There are instances where you cannot remove files from folders. If your computer is affected by a virus, the virus can tamper the settings present in your computer. Unauthorized operations will be performed on your file. You should go for good quality anti-virus software to remove virus from your computer.