By default, when you go to close a page within your workbook down a prompt is displayed asking you to confirm this action.  This is designed to prevent accidental closures of unsaved pages.  With the release of Build 51 a new option has been added to this prompt, which will allow you to delete pages without having to confirm it each time.

When you go to delete a page, the following window will display:

Tick the "Don't ask again." checkbox before clicking the Yes button to disable the prompt for future page deletions.