add_recipe() specifies the terms of the model and any preprocessing that is required through the usage of a recipe. remove_recipe() removes the recipe as well as any downstream objects that might get created after the recipe is used for preprocessing, such as the prepped recipe. Additionally, if the model has already been fit, then the fit is removed. update_recipe() first removes the recipe, then replaces the previous recipe with the new one. Any model that has already been fit based on this recipe will need to be refit.