If you have removed Norton Security from a device (i.e. PC), and now you would like to install it onto another device (i.e. another PC), you proceed as like you’re installing it onto an additional device.
If you’re sure that you will not use Norton Security again on the device it is being removed from, you can free up the license by going to Manage My Installs in your Norton account where you can remove the device from the list.
The installation process onto another device can be started from within your Norton account.