I understand that when you waive something you forego it or give it up. e.g.
I waive my [right to] free coffee.
I also understand that a waiver is a document stating that you waive your rights to something, but I read the phase waive off and I don't quite understand it.
The context was
personA: Live slugs!
personB: Waive off! Waive off! This is just a practice run!
I see that waive off means stop, or go away or something like that but I can't exactly put a specific meaning to it.
What does waive off mean?