1. Login to your Blogger Account
2. Go to Design > Edit HTML
3. Click on the Check box which says "Expand Widget Templates"
4. Now Find this line of code in your template( Use Ctrl + F )
<b:include data='feedLinks' name='feedLinksBody'/>
5.Delete this line
6.Save your Template and the "Subscribe to: Posts(Atom)" link will be completely removed from your Blog.