The handling of termination and change of employment can be found in the Statement of Applicability Module, in the Implementation method for control A.6.5 (in case this control is marked as applicable).
The implementation method in the SoA describes how the company will handle termination and change of employment (a text is suggested, but you can edit it according to you needs).
In general, conditions that remain valid after the termination or change of employment are defined in the agreements with suppliers and partners, and in the confidentiality statements signed with employees. The clauses for this purpose can be found in the template Security Clauses for Suppliers and Partners. You can find this template in Conformio by clicking the link Documents in the left panel, then clickling in "Templates for Manual Editing".