The user will disappear from the Users tab in Settings, and will no longer be able to login to Semble.
Any tasks assigned to the user are also deleted.
However, any letters, patients, users, invoices, or settings that the user created or edited will remain on your Semble.
If they are a practitioner then you will no longer be able to find any bookings for this practitioner on the appointments calendar. As with locations, we would suggest moving any upcoming appointments before deleting a location. The bookings will still exist in the patient record and will not be deleted.