Remove ads for one single post alone

I am having my blog at https://www.siteguide.us.
In my blog run by wordpress, I am using the ocean mist theme and in the theme’s index file I’ve included a php file using <?php include”something.php” ?>

something.php consists of ad code basically
The ad is inserted in every post by default
I do not want it to be inserted in one of the posts.
Also, in the text editor where I type in the post, PHP execution is possible as a result of the php exec plugin.

Is there any way I can prevent the ad from displaying in one particular post?

Thank you