Chat's can get very busy and sometimes, you just need a fresh blank page. Here is a guide on how to clear a chat ..
Log into WeAreX using your email and password.
Head to your messages by clicking the messaging icon, second bottom left.
Click on the group chat you would like to clear.
Click on the title of that Group Chat.
Scroll to the bottom of the page and click Clear Chat.
This will immediately clear all the previous chat for you, however the chat will still be visible to other members of the group. If you want the chat removed for all, you will need to DELETE CHAT.