str_replace value which starts with x and end with x

i want to use the str_replace function for change many value like this;

<p><a href="gogole.com">gogole</a>a ramdom text</p>

to

<p>a ramdom text</p>

or again

<p><a style="color:red;" href="stackoverflow.com">stackoverflow</a>a ramdom text</p>

to

<p>a ramdom text</p>

so how i can do it ? thanks