b56e63e2a9 removed -del for list options but it is still listed in the
list structs, which means that it is still tab completed on the CLI like
the other actions, and seems to behave like -set. Remove it so it is no
longer tab completed.
Also remove the description of -del from the help output of object
settings lists --(ao|vo|af|vf)-help, and update a comment.