Sorry to hear that you hate it! It's something we decided as a company that we want to keep, and even our VIP hosting clients like CNN and Time are required to keep the credits in tact.
You can't remove the footer credits, but you can add your own text or modify the look of the current text as long as it's still readable.
To add the line you mentioned above the other footer text in the Spun theme, you could add this to your Appearance > Customize > CSS editor:
content: "All Rights Reserved. Henry Heng Lu \00A9 2014";
The first block adds extra text. The second block makes it so the case isn't all upper case and tightens up the line height.