No prob. I can replace it. Don't forget to read the
Guide in the first post.
EDIT: Actually, I couldn't find anything missing in my corner, so I'm not sure which sign you meant. At any rate, I put a musical thing in the right corner, and added my own Every-Puzzle-Type-Known-To-EE Challenge on the left.
EDIT 9-18: Actually, as long as you don't save the world, you can delete whatever you want. If you made a mistake, and want to undo it, there's a button for "Load Level" in the "Modify Level" menu, and when you are satisfied with a section, that same menu has "Save Level" in it. Most likely, you deleted it, but didn't save afterwords, so it went right back to what it was before you got there.
Also, News in the first post:
I renamed the other available worlds, and I added a few things I forgot to my Every-Puzzle-Type-Known-To-EE Challenge (I'll have to write a guide to that, when I get a chance...).