In Symantec Endpoint Protection Manager (SEPM) Firewall policy MAC rule user is able to delete the active network services assigned to the MAC devices. This causes policy corruption and broken link in the SEPM Database.
SEPM 14.X
Precheck in the Firewall policy rules for Mac was missed in SEPM before deleting the Network Service.
This reported issue is fixed in SEPM version 14.4
If found any broken link in the SEPM database, contact support to fix it.
Check the SEPM firewall rules for MAC and verify if the Network services you planed to delete are not actively assigned to any of the groups in the SEPM.