The creators of WordPress (thanks Matt) in all their wisdom decided to inject a “Proudly Powered by WordPress” on every new install.
Not sure if it was vanity, their idea to give web designers work, or what. Bottom line is it’s a pain and millions of people have since had to google how to remove this annoying trait of a new install.
TL;DR
- Theme Editor
- Footer
- Remove the block of code
Reference
Remove Proudly Powered by WordPress from Free WordPress Themes