First off, give us the make and model of the router you are having problems with so someone with knowledge can assist you.

The only way to change the name of the device is from the setting within the device, namely your router you are having problems with.

Once you have that fixed, to remove a device from your preferred network is just a case on opening up the properties of the wireless connection in question and click on "wireless networks" and remove the preferred connection in question from the list presented.

Regards

Fred