How to turn off comments on particular blog post

IF you have a blog which have weekly giveaways and wants that the comments should end on a particular day and Now longer want to accept comments after that date.
How to disable comments on that post after a specified Date?

Quick Tip-Open the post to edit. At the bottom of the edit box click post options. You will have three comment options when there are comments already. Choose "Don't allow, show existing."