How to undo shortcut that you already typed in emacs?

Question

Suppose, you type a shortcut key in emacs (say M-x) and you realize that you did not want to do it. How do you undo a shortcut that you already typed?

I have tried Esc-d but that doesn't seem to do what I want. Typing C-g after a wrong input says that the shortcut is not defined.

What I want is a way to immediately come out of all the typed shortcuts and execute new shortcuts immediately.

I hope my problem seems clear.

Answer 1

Cancel is C-g in emacs no matter what the context is.