At the bottom right corner of the page, you should see an icon - it can be a message icon, a question mark, or an arrow down.
Click on it to minimize the chat window. ⤵️
Later on, if you need assistance, you can click on the icon again to open a chat.
If in case you do not see any icon, please try to refresh your page or go to a different tab (Campaigns, Subscribers, etc.).