To mute a chat and block a chat, you can follow the steps below: 

Muting a Chat: 

On an iOS device, you can swipe right on the chat list page to reveal the mute option. This option allows you to mute the chat. 

On Android & Huawei devices, you can long-press the relevant chat on the chat list page and select the "Mute" option from the menu that appears to mute the chat.