I followed the instructions on http://bt.custhelp.com/app/answers/detail/a_id/47521/c/346 for my wife's iPad and iPhone and I think (fingers crossed) they are working ok.
When I attempt to delete her account on her Mac, I get a message, which is not mentioned in the link, that says: 'Are your sure....deleting this account will remove its data from Contacts, Mail, Messages and Notes.'
Is it safe to do so or not?