I've had a bit of a weird glitch when a supply line has been added, but I'm certain I didn't do it.
The line's been added from Finch Farm to Oberland Station.
I'd just go and cancel it, but because it's a glitch of some form, there's no provisioner to interact with.
Oberland Station has two settlers, both of whom are farming.
Finch Farm has fourteen settlers, four of whom are farming while the remaining ten are running supply lines to other settlements.
I think this may have something to do with the fact that I accidentally killed a provisioner (from Finch Farm to Kingsport Lighthouse) when he wandered into the middle of a firefight.
Does anyone know how to remove the extra supply line?