In order to reduce history pollution, which an almost unbearable headache, I would prefer to vaporize stuff in there that I needed briefly but will never really need again. In the case of making a sketch, I'll set up a plane to orient the sketch plane to and then delete that plane. Unfortunately every time I make a change to that sketch, I get this error "Warning: Unable to reference parent objects that are deleted." It still lets me go on, but super irritating.
Any way I can remove parameters of a sketch?