You want to know how to move clients to a different Symantec Endpoint Protection Manager (SEPM) which has no association with the current SEPM.
Migration to an unrelated SEPM environment.
Option 1: Use a Communication Update Package from the new SEPM
Restoring client-server communications with Communication Update Package Deployment (broadcom.com)
Option 2: Upgrade the client and simultaneously reset the client-server communications settings
Create Client Install Packages to migrate clients and move them to a different SEPM (broadcom.com)