Find and replace part of inner div

How do I find and replace to remove inside div child element, keeping everything (all <p>*</p>'s) .  some times their is just on p element, and sometimes alot.
link to regex101

<div class="expand_collapse section_box">
     <h2>Animal </h2>
     <div class="box_content">                        
          <div class="expand_collapse section_box">
              <h2>Agent Facing</h2>
               <div class="box_content">
                  <p><a href="/Brochure.pdf" target="_blank">Animal<br>(bully breeds &amp; bite history)</a></p>                                                   
              </div>
          </div>
          <div class="expand_collapse  section_box">
              <h2>Consumer Facing</h2>
              <div class="box_content">
                 <p>content</p>
              </div>
          </div>
       </div>
   </div>
   <!-- Next Product -->

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I just want to remove:

 <div class="expand_collapse section_box">
      <h2>Agent Facing</h2>
       <div class="box_content">

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and

                           </div>
                        </div>
                        <div class="expand_collapse  section_box">
                          <h2>Consumer Facing</h2>
                          <div class="box_content">
                            <p>content</p>
                          </div>
                        </div>

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so keeping one or more of the 'P' elements inside the second div.box_content element.
I think I need to create a group for one or many p elements  (<p>.*</p>)  then replace with $1? So I keep the p's? (This does not work)
Can you provide a link to a resource to help me with regex as I do a lot of replaces/removals.

It would look like this when done.

<div class="expand_collapse section_box">
    <h2>Animal </h2>
     <div class="box_content">                        
         <p><a href="/Brochure.pdf" target="_blank">Animal<br>(bully breeds &amp; bite history)</a></p>
      </div>
</div>
<!-- Next Product -->

Select allOpen in new window

Thanks in advance.   I am not good with regex.