In all other block programming editors (Scratch, Snap!, Blocky etc), they all allow you to delete a loose block by dragging it back over to the left hand palette.
This catches me out in Node-RED, as I repeatably try to do this before remembering that I can't and then having to go to the effort of right-clicking and selecting Delete Selection!
Or even worser - having to take my hand off the mouse and press delete!!!
I realise that the goal is just to delete the node, however I don't see the rationale in returning it to the sidebar, it's not as though it would retain its config and allow it to be re-used.
A simple click of the delete key is a straightforward and quick way to do it IMO.
Can't deny that this would be a nice enhancement. Though I'd say that perhaps it would be better to be able to drag off the main panel.
I was wondering if it needed a confirmation dialogue but then realised that you still need to deploy anyway and so can simply undo. So no confirmation needed.
It would be nice thing and may really speed up workflow.
I think it needs at least settings to enable/disable that behavior thus it can happen accidently too often..
Or may be dedicated "drop off" area or something