Note: Please note that only Premium members can change between Meal Plans/Diets. Free users are offered the Lifesum Standard Diet. When you start using the app, the Lifesum Standard is activated by default.
Tap on the DIETS tab in the tab bar at the bottom of the screen and choose between the different Plans. If you have chosen a Diet and would like to change either the Diet or the Diet settings just go to the DIETS section again and choose the next Meal Plan/Diet.
This means that you cannot "delete" a Diet or Meal Plan - but if you ever leave the Lifesum Standard Diet and choose another Diet or Meal Plan you can always go back to how you started off by choosing the Lifesum Standard Diet again.