premise: At the request of the supplier of the Proprietary Information the receiving party shall immediately return all Proprietary Information which the receiving party (or an Authorised Person/Agency Authorised Person) has in its possession, custody or control including all materials (in hardcopy or electronic form) that incorporate any part of the Proprietary Information and, if required, destroy any copies of such Proprietary Information and materials and certify in writing that such destruction has been completed.