How to refrain operator from silencing alarms from the 'audible Alram' icon in the overview layout from OWS
Haven't tested; but try changing the "Silence" operation's permission in Aspect System Structure->Alarm & Event->A & E Presentation->Alarm and Event List category object, permission tab.
Default is "Operate" which can be changed. You can even create a complete new Permission and tie Silence to it.
Finally, give permission only to users that shall be able to silence.