A user can be disabled by following the below steps:
Go to 'Admin' > 'Practice' > 'Users' > Filter by the user you would like to disable > Select Pencil. See below:
Once you have selected the pencil the below dialog will appear. To disable the user simply un-tick the checkbox beside enabled. See below:
Within this section, you may also want to update the password and remove the login days by un-ticking the checkboxes beside the days for extra security.
NB: Please ensure the 'Has Appointments' check box REMAINS checked if the user has an appointment book.
To update, simply select 'save' and this will disable the user.