Outputs a new thing that is equal to
things with all members equal to
things input must be either a list or a word.
Because the members of a word are single characters, if
things is a word, then
thingtoremove should be a single character.
REMOVE does not remove multi-character substrings from a word.
SHOW REMOVE "b [a b c b][a c]
SHOW REMOVE "e "HelloHllo