Outlook doesn't support canceling meetings or appointments; you're expected to delete them when they are cancelled.
If you don't want to delete the meeting or appointment, one workaround to assign a category to cancelled meetings and then use custom views to apply a colored label in Day/Week/month view or use a strikeout font attribute in table view to items using that category.
Open the Define Views dialog and Create a new view or Modify the current view, adding Automatic formatting rules to change the text format or apply a colored label.
If you aren't sure how to customize a view, see Create a Custom View in Microsoft Outlook
Published February 9, 2005. Last updated on December 27, 2013.