[How to] make a participant who send only

My use-case is 1 publisher (send only) and other users (send and receive).
I can achieve “send only” with following code at publisher side:

let contrains: any = {

            colibriClass: 'ReceiverVideoConstraints',

            lastN: 0, // Number of videos requested from the bridge.

        };

Now publisher can’t view video from other users, but when I check traffic via “chrome://webrtc-internals”, there’s still incomming video streams (traffic) from others. Anyone help me! Thanks!