If you click somebody in a room you own, you will see that person's signature, pins, and four buttons below these. In the row of red buttons, on the right you should see a button marked "Boot." By clicking this button, it will immediately send the person clicked on from your room into their room. It will then take the booted person several minutes before they're allowed back into the room they were booted from. This option to boot is especially handy when other players are inconsiderate.