php two html tag remove

[kalster]

using php regex, i would like to remove everything within a <div></div> and including both div that contains "<hr> </b>" inside of the divs. notice the space between "<hr> </b>"

 

the following line needs to be removed...
        <div><b>username<hr> </b></div>
from a string but only if the div contains <hr> </b> both with a space between them
        

thank you

[.josh]

$content = '<div><b>username<hr> </b></div>';

$content = str_replace('<div><b>username<hr> </b></div>','',$content);