How can I remove the css style from the stirng?

 Hi,
 
I have a string value like this:

<div class=ExternalClassF87892EB6D6D4160B91215823E576689><div>I am
very good .</div> <div> </div> <div>I am very good
.</div> <div> </div> <div> </div></div>
 
How can I progamtically change this string to the following format?
 
I am very good .
 
I am very good .
  Thanks a bunch.   
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