You can refer to the following link for more details. https://www.koodomobile.com/en/help/how-to-set-up-a-guest-network

Thank you Milk Way, I already have a Guest WiFi setup. My question is related to: how to disconnect someone’s device in the WiFi. 

To disconnect someone from your WiFi, you would have to access the wifi router management software. Which wifi router did you have? If you can access to the software you can select which device to be removed.

Anyway, your wifi should have unlimited data. If there isn’t any security issue, I would let the device connect.

Thanks Dinh, the router is a white cylindrical from TELUS, it says Boost2.0. Can you let me know the wifi router management software or where to access it?