If you don’t want to get chat's push notifications, mute them or turn off completely.
To mute notifications:
Go to your Chat Page
Open the chat you want to mute
Click the Info icon in the top right corner of the chat's main dashboard. The Chat information sidebar menu will appear on the right
Click Notifications. The Mute conversation window will appear

Select the length of time you'd like to mute notifications for
Click Save
To unmute notifications:

That's it! You'll start receiving notifications again.