under windows-ntfs if you special characters in a filename… you can get into trouble deleting them (from command prompt it should always work)
under linux-ext3 you can run into similar problems if a filename (for whatever reason) contains „–“ (two minuses)
to remove them go:
rm -- --testings.html
The — option tells rm to treat all further arguments as file names, not as options, even if they start with -.