how do I delete the goose if they have grabbed my mouse?
hold esc
DO NOT CLOSE HIM WHILE HE HAS THE MOUSE
it will cause the mouse to get stuck here it was when you closed him only logging out/back in will fix it.
to close the goose any other time hold ESC for about 20 seconds top left you will see a message saying keep holding
if you re-open the game by using the arrow keys to navigate the menu your mouse works again