For personnel of type "User without calendar"
Delete their profile.
Create a new staff profile, making sure to invite them to join Booxi with the new login email; assign them an appropriate user access.
For staff of type "Personnel with a calendar" with NO user access
You simply need to edit their associated email address in their profile, as shown below:
For staff of type "Personnel with a calendar" with user access
Create a new staff profile (of type "Personnel with a calendar"), making sure to invite them to join Booxi with the new login email; assign them an appropriate user access.
*Important: If the initial profile has any upcoming appointments, re-assign them to the newly created profile.
Delete the initial profile.
*Important: it is important to follow this order because when you delete a personnel profile, their assigned appointments will no longer be editable (in other words, you won't be able to reassign them).