When you type OVERKILL in the command line, it will allow you to delete information that is overlaying other items in AutoCAD. Say for example, if a line is drawn and another line is drawn directly on top of it accidentally. By entering OVERKILL you can delete the second line or if you wish to do something else with it, there are other options from which you can select. This could erase unneeded information from drawings, cleanup your work environment and possibly delete unnecessary layers.