You can disable the option for clients to log calories burned when entering activity entries in the Lifestyle Journal. Disabling this option will also hide calories burned when displaying activity data synced from a connected Fitbit device.
1) In your client's file, select the Journals link in the left navigation menu:
2) Click the Edit journals icon in the top-right corner:
3) Click Edit next to the Lifestyle Journal:
3) Enable the "Hide calories burned for activity entries" checkbox:
4) Click Save Changes
You can also disable calorie tracking by default for new clients by following the instructions here.