You want to disable the LiveUpdate button within the unmanaged Symantec Endpoint Protection client user interface so that users can not run LiveUpdate by clicking that button.
This procedure is for unmanaged Symantec Endpoint Protection clients only. Disabling this button on managed Symantec Endpoint Protection clients should by done by modifying the client's policy on the Symantec Endpoint Protection Manager.
Follow the below steps to disable the LiveUpdate button within an unmanaged Symantec Endpoint Protection client's user interface.
Note: Symantec recommends that you backup the Windows Registry before proceeding.
Should you ever want to enable access to the LiveUpdate button with the unmanaged Symantec Endpoint Protection client user interface, you may modify the AllowManualLiveUpdate registry key and change the Value data to 1.
Note: Tamper protection needs to be disabled before changing/adding the registry.
Reference : Disable Tamper Protection