The thirteen default USDA allergens cannot be deleted. However, you may add, remove, or modify any non-default allergens that could benefit your staff and clients. Allergens are linked to specific ingredients, which are then associated with the recipes that contain them.
1) Associate allergens with ingredients in the Edit Ingredient page
2) When an ingredient that may cause allergies is included in a recipe, the recipe will show an allergen alert.
3) If you want to see which allergens are linked to recipes, click on the Gear icon, then Setup, then Allergens
4) Click on the blue icon under Associated Recipes
5) And you will see all the recipes associated with that allergen