If you just take them offline you can do this without having to rush.

Just change your WiFi password, don’t give them the new one and don’t update them lol.

You can't hardly use the TVs then. I've seen TVs that don't let you use the HDMI port without it being connected if you have a streaming dongle connected. Hopefully that practice has mostly died off now (Samsung used to do this on some models, iirc), but it's still a risk and only kicks the can down the road a bit.