When I signed up for BT broadband I was told I had to subscribe to the landline. This has not been used for a long time and I understand that it is now possible to sign up without the landline fee. Is it possible to reduce the monthly payment by cancelling the landline?
No, the landline is needed to carry the broadband, so if you cancelled it, you would lose the broadband.
Line rental is now included in the cost of the broadband, so you are not paying any extra.
At the minute the cost is the same with or without, you still have the line that supplies the broadband, it's the voice element for calling that is not included which makes up a small fraction of the cost.