How to easily block a device from the network

Okay, there has to be away to kick a known device off your network.I need to block my son's laptop from the internet as form of punishment. I know which device is his, there has to be away to revoke network permissions or suspend them for a certain amount of time without having to shut down the whole network. I mean if you see the device on your network, why cant you shut it off, especially since you gave it the key...pls help