How to implement OpenID Connect Back-Channel Logout

Hi Everyone,
I am trying to clearcut my client cookies upon logout, I found somewhere we can achieve this using the backchannel_logout. So I have setup the respective attributes on client setting, but it was not clearing my client cookies from the browser.

Backchannel Logout URL - client app url
Backchannel Logout Session Required. - ON
Backchannel Logout Revoke Offline Sessions. - ON

Please help me how to implement this backchannel_logout functionality
Thanks in Advance !!