Just figured out you can get rid of unwanted potion.Just drop someone onto table thats full of herbs ready for different potion and they will dumb old potion.Kewl.

That's really not a spoiler, since it's one of the tips that can be seen by clicking the mask on the main game screen:

"Empty the pot by dropping a villager on a table full of herbs."

Shame the villager has to be dropped again after the pot is emptied to start making the next potion, though. Still, I suppose we can't have everything, or there'd be nothing for the Guiding Hand to do.