You need to do this, probably because you have received a warning message from Google Adsense.
It could be, one of your blog posts have violated its program policies.
How To Block Adsense Ads On Single Blogger Post
There are two things which you have to do:
First you have to add div to Adsense code.
Second, you need to add a special JavaScripts at the end of any of the blog post which you do not want to show any Google Adsense ad.
IMPORTANT: Before you do any changes to your Blogger template, always backup of your Blogger template.
In case you screw up, you can always revert back to your present template.
How To Hide Or Exclude ONE Adsense Unit
1. First, you have to put <div id="AdsenseAds1"> and <div> between your Adsense code, as illustrated below:
<div id="AdsenseAds1">
<script type="text/javascript">
<script type="text/javascript"><!--
google_ad_client = "ca-pub-xxxxxxxxxxxxxxxx";
/* 160x600, created 9/20/11 */
google_ad_slot = "xxxxxxxxxx";
google_ad_width = 160;
google_ad_height = 600;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</div>
2. Now add this JavaScript at the end of the post which you don't want it to have the Adsense ad.<script type="text/javascript">
<script type="text/javascript"><!--
google_ad_client = "ca-pub-xxxxxxxxxxxxxxxx";
/* 160x600, created 9/20/11 */
google_ad_slot = "xxxxxxxxxx";
google_ad_width = 160;
google_ad_height = 600;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</div>
<script type="text/javascript">
var Ads1 = document.getElementById('AdsenseAds1');
Ads1.parentNode.removeChild(Ads1);
</script>
More Than One Adsense Unitvar Ads1 = document.getElementById('AdsenseAds1');
Ads1.parentNode.removeChild(Ads1);
</script>
For example, if you have THREE Adsense ad units on your page, then this is how it is done.
1. Similar to the above example, you have to add div tags between each ad unit.
<div id="AdsenseAds1">
Adsense code for ad unit 1
</div>
<div id="AdsenseAds2">
Adsense code for ad unit 2
</div>
<div id="AdsenseAds3">
Adsense code for ad unit 3
</div>
2. Again you need to add JavaScript at the end of each post which you do not want to show Adense ads.Adsense code for ad unit 1
</div>
<div id="AdsenseAds2">
Adsense code for ad unit 2
</div>
<div id="AdsenseAds3">
Adsense code for ad unit 3
</div>
3. This is what you need to add at the end of your post:
<script type="text/javascript">
var Ads1 = document.getElementByI('AdsenseAds1');
var Ads2 = document.getElementById('AdsenseAds2');
var Ads3 = document.getElementById('AdsenseAds3');
Ads1.parentNode.removeChild(Ads1);
Ads2.parentNode.removeChild(Ads2);
Ads3.parentNode.removeChild(Ads3);
That's how to block Adsense ads on single Blogger blog post.
var Ads1 = document.getElementByI('AdsenseAds1');
var Ads2 = document.getElementById('AdsenseAds2');
var Ads3 = document.getElementById('AdsenseAds3');
Ads1.parentNode.removeChild(Ads1);
Ads2.parentNode.removeChild(Ads2);
Ads3.parentNode.removeChild(Ads3);