CancelButton

CancelButton[]
represents a Cancel button in a dialog that closes the dialog window when pressed.

CancelButton[action]
represents a button labeled Cancel that evaluates action when pressed.

CancelButton[label, action]
uses label as the label for the button.

In dialogs created with DialogInput or CreateDialog, pressing Esc is effectively equivalent to pressing the Cancel button.

If there are several Cancel buttons in a single dialog, Esc will use the first one in the dialog.

Create dialog input and use CancelButton to cancel the action: