Roger Mills explained on 24/09/2019 :
I could potentially dismantle it myself, and take it to the tip but bits of
it are likely to be pretty heavy and I don't wish to risk injury either to
myself or to the property. So my preference would be to get this firm to
remove it as long as they're not going to wreck the joint in the process.

Hence my original question.

If its in working order, and a straight run, why not sell it?

The straight runs are easiest to remove, the most common and the most
saleable. Removal is just a matter of dropping the seat off the rail,
releasing/ dismantling the rail. Not difficult.