Note: As Amanda points out in the comments, it is not a good idea to do this for SEO and accessibility reasons.
In Genesis, entry titles on single Post pages get wrapped in h1 tags by default.
What if you want to change these to h2 instead like this?
Just add the following in your child theme's functions.php:
Hi Sridhar,
The reason post titles are wrapped in on single views is because the post title is the most important heading on that page. I would encourage not changing this wrap, both for SEO reasons and for accessibility reasons. For background, see: http://genesis-accessible.org/2015/07/genesis-2-2-accessibility-changes-and-features/ specifically the section on heading structure.
Thanks for sharing that Amanda.