You can collapse a chat conversation to allow you to start a new conversation or carry on multiple chat conversations simultaneously. You can permanently close a conversation when you're done chatting with someone.
Step 1. Open the Collaboration Center to the Chat tab. Click the gray X button to the right of the name of the colleague with whom you have a chat open. This will collapse the chat while retaining the conversation. You can re-open it later by clicking on the colleague's name in your Chat tab. In this way, you can move between multiple chats.
Step 2. To permanently close a collapsed chat conversation and clear it from the Chat tab, click the gray X button next to the participant's name. The chat will disappear from the panel.