How do I delete access to one accountant and add another ?

Hi Caroline4, 

You can delete the an accountant from the file in Manage Users screen on the Accounting Firms tab. Below is a link to a detailed article regarding adding, removing and editing users in QuickBooks. 

https://quickbooks.intuit.com/community/Manage-your-account/Add-delete-or-edit-a-user/m-p/263131?advanced=false&collapse_discussion=true&filter=location&location=category:community-au&q=delete%20an%20accountant%20user&search_type=thread

Have a lovely Monday!