How to remove plants created in the Flora Editor?

Plants that I created in the Flora Editor appear in the Creature Stage and “break up” the screen (e.g., if my creature walks past a pink plant, the textures are torn apart by pink “walls”). When I try to delete plants through the Sporopedia in the game, they reappear the next time I open the Sporopedia. Deleting the Plants folder manually did not solve the problem. Where then are the plant files to be deleted?