On the machine that uses the WiFi you want to stop using, ask the ISP you want to continue using how to connect to their WiFi hotspot or router.
At present, I have two different broadband subscriptions for two PCs in the house. Both have their wi-fi routers. I end up paying the service provider for both connections.
Can you please guide how I can use just one of the connections to access internet on both PCs and then discontinue paying for the second subscription?