As host, when the meeting is over, remind your guests to click LEAVE MEETING in the upper left corner of their browser window.
Only Guests see the LEAVE MEETING option. You will want to conclude your meeting by instructing guests: "To leave, click LEAVE MEETING in the upper left corner".
When your guests leave the meeting, they will see the message shown in the screenshot below.
How do you get rid of the guest who never leaves? Your best option is to right-click on the guest avatar and select Disconnect Guest.