Cannot delete harvested plant?


today I tried to delete plant which is harvested from farmdesigner. I get such an error message:


is this a bug or intention that points that are used in sequences cannot be erased?



Not a bug. You are correct in that you cannot delete a plant (or sequence, or event, or regime or anything) that is used in or is dependent on any other sequence or such.
I have not had to do so yet, but I would imagine that if I was to harvest a plant, I would have to first remove it from any sequence that affects it first (Watering, checking soil moisture, taking pictures, etc.). After that, I would be able to delete (remove) the plant from the Farm.