Want to remain outside tags only.Check and remove all inside tags!

Question

For some reasons My web page has some un-normal code structure.Just like this:

    <p>
        <strong>
            <strong>some word</strong>
            is here
        </strong>
    </p>
            ......
    <p>
        <strong>
            <strong>I am </strong>
            here too.
        </strong>
    </p>

and these code happened in multi place. How can I to remove the inner 'strong' tags and remain the outside.

Thank you very much!!