Syntax: DELETE [ INTEGER1 INTEGER2 ]
or:     DELETE HISTORY [ ! ]
or:     DELETE HISTORY INTEGER1 INTEGER2
or      DELETE WORD

   Delete commands INTEGER1 to INTEGER2 (inclusive) from the history
buffer.  If the INTEGERs are not present, delete the DELETE command.
We recommend using the macro `del', which deletes the previous command
if used without arguments. If the INTEGERs are negative they are
interpreted relative to the current command, so -1 is the last
command.

   The DELETE HISTORY commands are identical to the DELETE commands,
except they themselves DO appear on the history list; they are
preserved for backwards compatibility, and to allow DELETE HISTORY \n
to be used to keep commands off the history list.  If a macro contains
a DELETE HISTORY, or calls a macro that contains one, or ... the macro
will not appear on the history list. If there are two (or more)
occurrences of DELETE HISTORY only one command will be deleted, unless you say
DELETE HISTORY ! in which case you can delete as many as you like.

   DELETE WORD deletes the vector WORD (see SET WORD or READ WORD for
how to define vectors), MACRO name DELETE is used to delete a macro,
DEFINE name DELETE deletes a variable.