To unsubscribe from a hub's messages, you must leave the hub.
You can leave a hub following these steps:
1. Visit the My Profile under the drop-down on the top right
2. Scroll down and visit Hubs on the right-hand side. Then click edit.
3. Click on leave hub next to the hub you prefer to leave.
By removing yourself from the hub, you are also unsubscribing yourself from last communications list.