2.3 I would like to know if there is a way to "erase" the REDO stack? For security reasons I would like to prevent sensitive commands from being seen by a LISTREDO command.

Either

:setvar hpredosize,0

or

:setvar hpredosize,1

followed by

:setvar hpredosize,n

where "n" is the size you normally use, will do the trick.

Obviously this could be set up as a UDC or command file, if it is something you do often.