How to disable a field in Search box of Manage Project Costs Page?

Summary:

We have a requirement from client, where they want to disable a field (Person Name) from the search criteria of "Manage Project Costs" page. We tired editing that field from Page Composer (through Sandbox) we are not able to do so.

Can someone please suggest what needs to be done to achieve this? Please see screenshot attached to view the field that needs to be disabled.

Any help is really appreciated!!