My roommate quit paying for wifi and I don't want him to have access anymore. Will changing the wifi password make all users have to enter in the new password? If not how else can I kick his devices off?
Yes changing the WiFi password would make all devices that are connected to the WiFi have to re-enter the password for each and every device.
Now, their is another option. You can just Block the device all together you're roommate won't be able to have internet access at all. But it's tricky for one to do that. It involves with the mac address. Because every device has a mac address that is assigned to each of themselves. It's not that hard to enter the mac address to manual. But, in order for you to do that. You will need to know which mac addresses belongs to who is who. So you will have to go to the system settings of the device and write it down. Then go back to your router and manually put the mac address in there yourself. But you will have to do that for each device for your roommates.
Their is another way also. If you have a router that can see the mac address. Then you can just tick the little box that say's Block device? You press Yes. Then it is fully blocked and no internet can go to it or from it.
It's just you got to know who's mac address of the devices itself belongs to who and such as. I hope this helps you in some way. Good luck and as always!