How to remove a sentence that I put at the bottom of "powered_by_vbulletin" phrase?
 

I put a sentence in a further line at the bottom of the "powered_by_vbulletin" phrase in my forum. Now I want to remove it* but* if I look for it through the phrase manager* I can't find it. Even if I search it through the "search in phrase": the result of the "powered_by_vbulletin" phrase does not show my further line at the bottom. Instead it always appears at the bottom of my forum.
Is it possible that by my mistake the further sentence is nested somewhere else?
What can I do to find out my sentence* editing the keywords somewhere (I would like to avoid to copy the default test in the "powered_by_vbulletin" phrase* to get rid of the sentence that I want to remove)?

thanks for help