1. Login to account wordpress.com --> Click My Site --> Click on one of the blogs that you want to delete.
2. Scroll your mouse and find the Settings menu. Next at the very bottom of the page, there is the Delete Site menu. Click on the option to delete your blog.
3. The system will then ask you to make a backup, or immediately delete the blog by clicking the Delete button.
How to delete a blog at Blogger.com :
1. Log in to Blogger.com then click the blog that will be deleted. Then click Settings - Other or Settings - Others.
2. Still in the same panel, find and click the Delete blog menu or Delete blog.
3. Finally click the Delete this blog button.