You can reset the site yourself or you can ask the staff to empty your site.
Note: Please keep in mind this action is permanent.
If you want to do it yourself, you can delete all of your content from your site and still keep your current WordPress.com address by performing the following steps:
Delete all posts
Delete all pages
Delete all categories
Delete all tags
Delete all media
If you want to have the staff do this, please add the modlook tag when you create a thread on WordPress.com support. You will need to be logged in to the user account you created the site with, confirm the URL of the site you would like them to empty, and that you understand this action is permanent.
Read more about emptying your site: https://en.support.wordpress.com/empty-site/
Due to the differences between the free hosted blogs offered at WordPress.com and the self-hosted and self-installed version of WordPress supported here, if the information above doesn’t help, I recommend asking WordPress.com Support.
