Ahh! Copyrite. Copying is the best form of flattery there is as long as it is not to steal. I could be wrong but all themes carry that message but I do not believe it has to stay.
It is good form to let the creator get credit but if you change the theme by editing I believe you should remove it as what you do to CC's original theme they may not wish to be associated with.
Like all companies CC has a standard they wish to maintain and when they release their themes for use it is their good name that it advertises.
I always believe that if you have a fair play policy you cannot go far wrong. "Give to Ceasar what is Ceasars"
The Guy from OZ
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