Netflix makes it easy to watch your favourite shows on just about any device. If you forget to sign out of a device you don't use anymore, Netflix also makes it easy to log out of all your sessions at the same time.
How-To Geek shows you how it's done, but it's pretty easy. Just navigate to your Profile, then hit "Your Account." On the next screen, you'll see an option to "sign out of all devices."
The only problem is, Netflix says it can take up to 8 hours for the changes to take effect on all devices. It will also log you out of your current session, so you'll have to log back in. For more detail, head to the full post at How-To Geek.