Remove Widget Title

Looking for how to remove the widget title that shows in the sidebar area. (please reference: http://www.projecthappiness.org/project-happiness-blog/ )

Specifically, I am looking at the “Popular Posts” area. If I could change that to an <h2> tag and center it I would be fine also.

Thanks,

Tra

https://ww.wp.xz.cn/plugins/top-10/