A staff member resigns — how do I revoke their access?

Revoke their rights from the users menu in the tenant panel. From then on they cannot sign in to your school, while their work stays: payments they recorded, invoices they issued, and changes they made still carry their name.

Because every staff member has their own account, there is no shared password to change en masse after somebody leaves. Other staff members' roles and branch limits are untouched.