How do I use create a trigger that creates a hero after a player selects the button in the menu? How do I remove the button after that?

menu = dialog ?

if yes:
- there is a dialog item event. You can select click in it. Then you have to compare the clicked dialog item with your buttons. So you had to save the buttons in variables after you created them.
- hide the dialog for the player or destroy the dialog

if no:
- what's "menu" in your case?