Deleting an instrument / stave / part

Hello
I created a new part simply to swap some notes between two other parts (I copied them from part 1 to the new part, then pasted from part 2 into part 1, then pasted from the new part into part 2)
So now I have an unused part, which I would like to delete, but I can't see how. For the time being I've turned off the display but that doesn't feel like the right way to deal with it.
Can anyone tell me how to do that?
Thank you