We need edit a functionality of giving createORselect Business Workspace of the BusinessWorkspace widget, for this we need to edit the OOB widget. Can you please guide me how can I edit the widget using SmartUI SDK.
you would need to use the Smart UI SDK to extend / override the widget as appropriate. Have you used the SDK before ? if not, perhaps the course https://www.opentext.com/TrainingRegistry/course/details/2928 may be of interest.