Subscription cancellation

I haven't even been able to use since I agreed to the subscription because it turns out my computer device is too old and therefore not compatible with this app. I have no devices linked to lightroom, nevertheless Lightroom keeps charging me money from the Subscription, I want a full cancellation since it has been useless, but Lightroom won't allow me at this time, since my payment could not go through. I don't want this service and I'm not even supported by techincal team throughout this process.