Thanks for your posts - I must admit, your question even though rephrased is rather confusing so I apologise if i have interpreted it incorrectly.
As @Graham_A advises earlier, you're unable to physically delete a device from device management - you can only replace with a new one.
When it comes to using a browser to use TVGo, it can be quite complicated; If you register a computer using a browser, you’ll need to use the same browser with Virgin TV Go. Using a different one will be seen as a different device. Also, if you clear your cache and cookies, this can also be seen as a new device.
What can assist with this is you can rename the device when you are registering them.
It would be your choice which "device" you wish to replace - the system will not make that decision for you.
To replace a registered device:
Sign in to Virgin TV Go on the new device using your primary My Virgin Media username and password
Choose a Live TV channel or On Demand show to watch