I see tons of players do this, but I don't know how.
Say I accidentally hotkey 1 spawning pool, and can't delete it because it's the only building/unit in on that hotkey. I could always hotkey another unit and then take away that one, but it takes too long.
I've seen pros do it, how do I clear one hotkey COMPLETELY no matter how many things I have on it? (like 1 unit or more bothers me the most)