rm ABC*

[utzoo!decvax!decwrl!turtleva!ken]

The file you have a hard time removing (ABC?) has some kind of unprintable
character in it; ls senses that it isn't printable and puts a '?' in place of
the unprintable character.  On earlier UNIX systems, there used to be a program
called "dsw" (a program with questionable etymology), which allowed you to
interactively delete files in the current directory.  "rm -i" is an attempt
to consolidate all the different types of removal programs, but it doesn't
fully take the place of dsw, because it doesn't change the unprintable
characters to a '?'.  Therefore, when you say "rm -i *", you never see "ABC?".

One suggestion is to do an "od -c .", and look for the file with the
unprintable character; then you can use one of various quoting mechanisms
to specifically delete the offending file.

Another is to find some sort of pattern that can uniquely describe the file,
such as "*BC*".  Try it out with "ls" first, then with "rm".