Can a player clear an input setting on the launcher dialog?

You can edit a game's input settings on the launcher.

You get to set a Primary and Secondary button for each action.

My secondary buttons start off blank by default.

Is there any way to reset an entry back to blank, by using the launcher dialog?

I've tried selecting items, without double-clicking, and then pressing delete, backspace, or escape. Doesn't clear it. If you double-click an item and then press any of those keys it sets them to be the button! Which makes sense.

So, is there a way to clear input settings without resorting to messing with the registry?

Note, this is not a question about input settings in the editor. This is a question about the default launcher for a built game.